Although it’s not news that Yahoo has been readying a new version of its homepage and has spent a lot of time doing so–in fact, it’s gone all Handy Manny with a whole lot of test renovations–the Internet giant begins the massive rollout of it tomorrow.

The official launch of what was code-named “Metro,” which Yahoo had previously said was coming in the fall, will take place on an opt-in “beta” basis for the hundreds of millions of users in the U.S. and will be extended to France, the U.K. and India later this week.

When users log in, they will get a choice–for now, there will be no forcing it–to switch over to the new version, which Yahoo’s Tapan Bhat, SVP of Integrated Consumer Experiences, said in an interview with me today by phone, is the “the most fundamental change to the homepage ever.”

And, indeed, the new look is much different, even than previous launch candidates, featuring an almost complete rejiggering of the look and feel of the most important page at Yahoo (YHOO) and one of the most trafficked on the Internet.

The change is an important one for Yahoo, since its front page is perhaps its most powerful calling card to users and advertisers, as well as to Wall Street. Its homepage gets 330 million unique visitors every month.

Yahoo has redone its homepage many times since its founding in the mid-1990s (you can see the various incarnations of it here), but this new design is perhaps the most dramatic.

(See screenshots of the new regular page and one with a Facebook app featured below; click on the images to make them larger.)

The most striking change is a prominent left-side “My Favorites” area, with 65 specially designed applications that users can customize, including giving a quick hovering glimpse of email, stocks and of third-party sites like Facebook.

Not quite a dashboard or exactly a social networking page, it feels a little as if Yahoo took a browser tab or a toolbar, put it in a vertical format and gave it some great functionality.

Full disclosure: All Things Digital, as well as several other Dow Jones news properties, are in its special alphabetical apps gallery, although I had no idea it would be there.

Yahoo also allows users to create such widgets on the fly from most any Web site and they can have up to 36 apps on the homepage.

There is advertising in the boxes that pop up when hovering over these apps, which is a way of dealing with the issue of purposely sending users away from Yahoo rather than keeping them there. It is a much better version of that trap.

“We want to be the center of people’s lives online and want to do it in an open, innovative way, all while providing a compelling experience,” said Bhat. “It marks the beginning of a renaissance of Yahoo, a renaissance where every pixel matters.”

After looking over the history of Yahoo’s homepages since 1994 (see them all here), it has pretty much told a story of a site with increasingly smaller font sizes and more stuff packed on it.

“It had nothing to do with the user, but what Yahoo wanted the user to do,” said Bhat, rather frankly.

Thus, he said, everything going forward will focus on what the user wants, which, he explained, essentially boils down to a “my world” and “the world” outlook.

In the my-world bucket: Email, favorite Web sites, stock info. In the the-world: General news, search, what’s hot.

But, unlike its highly customized MyYahoo product, Bhat said that Yahoo wanted to make it easier for users to create a page where “there is destination for everything you are about in just a click or two.”

The programmed “Today” module remains, although users can indicate which kind of information–finance, news, entertainment–gets top billing.

The module is also localized, depending on the user.

“We wanted to provide broadcast and narrowcast in one place,” said Bhat.

That includes updating status, right from the homepage, including integration with social networks such as Facebook and MySpace.

But–in a very big mistake–there is no ability to update status to the popular microblogging service Twitter on this part of the homepage, as yet. You can make it an app, though, as Twitter can appear in your Yahoo updates.

And there is a big advertising module still on the right, along with a what’s-hot section. And, finally, there will also soon be complete two-way syncing with mobile devices, said Bhat.

Interestingly, although CEO Carol Bartz has often said internally that she does not like the color purple, which has been the company’s signature one since its founding, the main page keeps up the violet tradition with a lighter tone.

“Yahoo’s color is purple and it is known for that,” said Bhat (deftly not taking my delicious bait).

As to why it has taken so long to get its front page redone–it was originally set to debut late last year–Bhat noted that such a major shift of such a trafficked page was, well, complex.

“It involves bringing users along and also rewiring everything within Yahoo,” said Bhat, who gave Bartz credit for turbocharging the effort, since she first arrived at the troubled Silicon Valley icon in January and quickly put the brakes on the planned launch. “Now, we are looking at Yahoo holistically, all centered around the user.”

Time will tell if it is a success, but it is certainly a good and even innovative effort, in much the same spirit Microsoft (MSFT) has had with its new Bing search offering.

And while some might complain that it is not cutting-edge enough, it seems just the right amount of rejiggering and open feel for the mass of users it serves.

For Yahoo, at least when it comes to this one, change is indeed good.

In early discussions that began in the last several weeks that apparently included a face-to-face meeting last week, Yahoo CEO Carol Bartz and Microsoft CEO Steve Ballmer are finally talking about search and also advertising partnerships the companies could possibly strike, said several sources with knowledge of the situation.

According to a variety of sources, the talks between the pair (pictured here) and other execs at both companies are preliminary and wide-ranging, focused on what kind of commercial relationship Yahoo and Microsoft could have in the future.

But, cautioned sources close to Yahoo, the discussions are not about a renewed acquisition attempt by Microsoft and also might not result in any deal.

In any case, investors will likely cheer any kind of productive re-engagement between Yahoo (YHOO) and Microsoft (MSFT), which has been lacking since a tense takeover effort by the software giant went south last year after an ugly battle that soured relations between the two companies.

“It’s long past time,” said one outsider who had been told of the discussions. “With Google’s huge market share, these two need to work together and the problems they had should be put in the past.”

Both Yahoo and Microsoft declined to comment about the talks.

The change in leadership at Yahoo has helped, especially since Bartz–a Silicon Valley veteran with much deal experience–has none of the baggage from the takeover battle that previous management was carrying.

Microsoft seems to have also moved on, working on a massive redesign and relaunch of its search brand, under the internal name Kumo, an effort that has included the hiring a whole lot of talent in the arena, mainly from Yahoo, in fact.

That includes Qi Lu, a former Yahoo tech star, who is leading all of Microsoft’s online efforts.

All of this means that a relatively green-field approach is now possible.

Thus, sources said, the talks include many scenarios, such as one in which the companies swap online advertising assets and deliver services to each other.

In that interesting plan, Yahoo might take over all of Microsoft’s display and premium advertising business to sell along with its own, while Microsoft would run the search advertising business for the pair.

Such a deal, which plays to each company’s strengths, would bind the two closely together, even though they still compete on many other fronts in the Internet space.

It also joins their forces, creating a sale that is much more attractive to advertisers and allows for better competition against search powerhouse Google (GOOG).

And while Ballmer has publicly said repeatedly that Microsoft is interested in buying either Yahoo’s search advertising business or search outright, sources close to Yahoo said the company is still determined to maintain control of the important search business and the massive traffic and critical data it provides.

That is especially true, given that Yahoo is the No. 2 player, with a much larger share than third-place Microsoft. According to recent surveys, for example, Google has a 63 percent share, while Yahoo has 20.6 percent and Microsoft eight percent.

But it is also in Yahoo’s interest to move fast, since its search traffic could be declining soon.

According to a story by Dow Jones yesterday, citing a comScore (SCOR) report, recent toolbar distribution deals with computer makers Hewlett-Packard (HPQ) and Acer by Microsoft and Google respectively, will have a negative impact on Yahoo.

The story said that Yahoo “could lose up to 15% of its search traffic over the next 12-to-18 months after failing to renew deals with two computer makers, blows likely to hamper the Internet giant’s efforts to remain a viable competitor in search advertising.”

But even as he directs aggressive moves to put even more competitive pressure on Yahoo, Ballmer has been unusually deferential in giving Bartz a lot of time to come to the table.

Nonetheless, he cannot seem to stop talking about it either.

At a recent conference in mid-March, for example, Ballmer said:

“It’s really about getting the pooled volume, because you actually can improve your product faster if you have more users….If you have more advertisers, you can improve the product as well….There are returns to scale. And putting the scale together is valuable.”

But, in that interview, Ballmer also said that he had only talked to Bartz briefly since she was hired in January–congratulating her on the new job and mentioning that he’d love to talk about a deal.

And, at another meeting with Wall Street analysts earlier, he went even further:

“You all know that I would like to figure out how to pool somehow Microsoft and Yahoo. I’m not talking about doing an acquisition, blah, blah, blah, back to search deals, blah, blah, blah, I don’t know if anything is going to happen. I’ll short-circuit the whole conversation, but the fact of the matter is, these two guys [Microsoft and Yahoo] should somehow figure out how to get together and create more competition for this guy [Google]. And I’m hoping perhaps that that’s a reasonable conversation to have with new management at Yahoo as Carol comes onboard.”

In contrast, Bartz has played her hand very close to the vest so far, at least publicly, often discounting any effort to split up Yahoo.

In fact, at a Morgan Stanley (MS) tech conference in early March, she said:

“I am not going to negotiate with my 55,000 favorite friends….We’re going to negotiate as companies negotiate–and that’s privately. If something happens, you’ll know it then. Until then, there is no comment.”

(By the way, both Ballmer and Bartz have agreed to be interviewed onstage–separately, of course–at the D: All Things Digital conference in late May that Walt Mossberg and I run–so we will be sure to try to get one–not that they would give one!)

Here’s a video interview I did yesterday at the San Francisco event where Yahoo finally launched a lot of the new open and social elements that it has long said it was injecting into its most popular products.

BoomTown talked with the key movers of the initiatives: Ash Patel, Yahoo’s EVP of its Audience Product Division, and Tapan Bhat, its SVP of its Front Doors, Communities and Network Services.

(You can see screen shots and an official Yahoo video of the new features here.)

The initiatives Yahoo (YHOO) finally released into the wild have been long in the making, first discussed as just vaporware by Yahoo CEO Jerry Yang at last year’s Consumer Electronics Show in Las Vegas (see that video below too).

Yahoo also hosted a session at its Sunnyvale HQ about its open plans in the fall.

And, after the longest of gestation periods, they arrived yesterday, in an impressive rollout.

The changes include some very deft rejiggering of Yahoo Mail, called a “smarter inbox,” with a new dashboard welcome page, easier ways to make connections, more filtered views, updates and third-party apps integrated into the application.

I thought the changes to the mail product were the most interesting, especially given the hundreds of millions of people using the product. It’s an interesting choice for a social entry point, aiming to give nonsocial-networking types enough of a taste of it without inundating them.

Of particular note were the third-party applications, such as for WordPress and Flickr, that launch nicely right in the email program.

Also cool was one app from Xoopit that surfaces old photos and photo links lost in the musty archives of old emails.

Yahoo also debuted an enhanced version of the homepage (previously announced in September) and My Yahoo, as well as a new toolbar and socialization elements added to its popular media properties.

It remains to be seen how popular these changes will become, especially since many consumers already have their social-networking lives on Facebook or MySpace.

In addition, both Time Warner (TWX) online unit AOL and Microsoft (MSFT) have rolled out similar social and open changes to their sites recently, making it super-confusing for everyone.

But, better late than never, I always say, so here’s Bhat and Patel talking about Yahoo’s new stuff.

I had to load the video onto YouTube, as Brightcove had snafus (also below is Yang talking about the concepts at CES in January 2008):

Tapan Bhat and Ash Patel

Jerry Yang at January 2008 CES

(BoomTown interviewed top Yahoo execs Tapan Bhat and Ash Patel about the moves here.)

For a look-see, here is a Yahoo (YHOO) video about the launch and some screenshots of the changes (click on the images to make them larger):

Yahoo’s Official Video on Open and Social Launches

Yahoo Mail Main Page

Yahoo Mail Inbox

Xoopit in Yahoo Mail

Toolbar Notifications

Media Integration in Yahoo TV site

Open Applications

While rumors of its impending re-sale have apparently been greatly exaggerated, what’s true about StumbleUpon is that its new Web-centric look and feel and a new partnering program represent a major shift for the online discovery service.

The San Francisco-based company, which was founded in 2001 and sold to eBay last year for $75 million, is announcing tonight that users will no longer have to register or download its toolbar to “stumble” the Web.

Users can now simply start on StumbleUpon’s site, for example, and stumble all over the Web using their Web browser as guide rather than a toolbar.

The move is being made simply because most Internet users are increasingly loath to install Web plug-ins like toolbars, a requirement that naturally has slowed the growth of StumbleUpon’s service over time.

Currently, StumbleUpon has about six million registered users, although only a fraction of those are responsible for the approximately 12 million daily “stumbles,” all using a toolbar.

“We wanted to attract users who do not want to use a toolbar, making it easy so they could use the service right from the get-go,” said Garrett Camp, co-founder of StumbleUpon, in an interview with BoomTown earlier today.

Camp noted that that the toolbar–which has been downloaded between 11 and 12 million times–has seen that growth slow over time. Nonetheless, it is not being eliminated either.

“[Toolbar adoption] was still growing, but not accelerating,” said Camp. “Being able to stumble without one was the biggest feedback we got from users.”

Along with the Web-stumble change, StumbleUpon is also unveiling a redesigned homepage–see an example of it below; click on the image to make it larger–which is an attempt to make it more of a destination.

With the new look, visitors can find content by topic and more related to interests. Other changes include a new look for profile pages, as well as user reviews, rating and comments.

Along with its distribution shift and site renovation, StumbleUpon is unveiling a partner program called StumbleThru that will allow visitors to discover content within those sites without going to StumbleUpon.

Sites–starting with HowStuffWorks.com and the HuffingtonPost.com and followed within weeks by RollingStone.com and National Geographic–will display a StumbleUpon “badge” or custom widget.

It is not unlike similar buttons that now dot Web pages from news discovery services like Digg, which users can click to find related pages.

Essentially, much as Google (GOOG) delivers custom search within Web sites, StumbleUpon is offering custom surfing, giving publishers StumbleUpon technology to allow its users to surface content within their sites that is often deeply buried.

As to the blog reports that eBay (EBAY) had put StumbleUpon up for sale after owning it for a little more than a year, Camp essentially dismissed them, noting that the unit is still operating as an independent subsidiary of the auction giant.

“They have given us a lot of runway,” said Camp.

Here is the new front page of StumbleUpon:

Also, here is a video I did last year at the exceptionally noisy (sorry!) party that StumbleUpon threw after it was sold to eBay a little more than a year ago: