Facebook CFO Gideon Yu (pictured here) is leaving Facebook, as the company announced internally today that it was replacing him and searching for a new CFO on the path to an eventual IPO.

The Wall Street Journal also reported the news, noting that the huge social-networking start-up was looking for a CFO with “public company experience.”

But several sources within the company said the departure was more due to an increasingly strained relationship between Yu and Facebook founder and CEO Mark Zuckerberg over strategic disagreements about a wide range of issues, from increasing advertising revenue to fund-raising discussions with investors.

“At Facebook, you’re either with Mark or you’re not,” said one source at the 800-person company, located in Palo Alto, Calif., and founded five years ago. “And, if you’re not, you leave.”

As a sign of that, Yu was out of the company HQ immediately today after a meeting, said several sources.

Facebook confirmed the move in a statement, focusing instead on its hope for an IPO sometime in the future:

“Facebook confirms that CFO Gideon Yu will be leaving the company. Gideon has played an important role in helping us achieve our financial success, building a strong finance team and establishing the core financial operations of our company. We are grateful to Gideon for his contributions to Facebook and what we are trying to accomplish. Despite the poor economic climate, we are pleased that our financial performance is strong and we are well positioned for the next stage of our growth. We have retained Spencer Stuart to lead our search for a new CFO and will be looking for someone with public company experience.”

In addition, trying to stanch the rumors of its financial weakness and need to raise more funds, Facebook said in its internal memo to staff that it was on the path toward a public offering soon, with revenue growth up 70 percent in 2009 and EBITDA profitability this year, and that it would be cash-flow positive in 2010.

The memo also painted Yu’s departure as another step toward its much anticipated IPO, although it is clearly an ouster of much more complex internal reasons about how Facebook is run.

Facebook has had a lot of those in its short history.

From come-and-then-gone Google tech exec Ben Ling to former COO Owen Van Natta to the pair who started Facebook with Zuckerberg, the fast-growing start-up has seen more executive turnover and turmoil than most big companies.

In fact, Yu–who was an exec at both Yahoo (YHOO) and YouTube and integral to its sale to Google–replaced former CFO Mike Sheridan in 2007, in another case of a key exec being replaced.

Some inside and outside the company were quick to blame COO Sheryl Sandberg for Yu’s departure–probably due to the fact that the pair’s relationship was initially tense when the well-known Google exec arrived a year ago. That has been much less so of late, sources said.

And while Facebook can be a highly political place, with an unusual level of passive-aggressive infighting among execs, it is also a place where Zuckerberg and his wishes firmly hold sway.

And those wishes included the fact that Zuckerberg has long and publicly maintained that Facebook’s growth was paramount over a focus on monetization of the service.

Yu is known internally to be more conservative fiscally, pushing on Zuckerberg to ramp ad revenue more quickly and to consider a range of options outside of IPO, including selling the company.

Many current and former execs had hoped the company would IPO, a process that has been dragged out due to the weaker economy. But–barring that–many had also hoped it would sell to a larger company like Google (GOOG) or Microsoft (MSFT).

In fact, Microsoft has expressed interest in buying Facebook many times, and it was Yu and Van Natta who were key to getting the software giant to outbid Google to invest in the company at an astounding $15 billion valuation.

After raising more than $500 million previously, Yu has more recently been busy working with top execs on the best way to raise more funds for Facebook, in order to allow it grow faster and give it a deeper financial cushion.

High user growth has blown past Facebook’s internal projections, which is both an audience blessing and a cost curse.

But that fund raising has been at a much lower valuation and in a very weak economic climate, adding to stress internally at Facebook, many said.

Yu has held a number of meetings with investors, many of whom have told me they have asked him consistently about the monetization issues at Facebook and exactly when Zuckerberg would turn on the ad spigot at the service.

Yu has also has been involved in some recent debt financing of equipment, which is not as unusual for a fast-growing company as some recent reports have portrayed it, although that might also have been a source of tensions.

How to answer prospective new investors has probably been at the heart of his problems with Zuckerberg, who has been known to run hot and cold on top managers, especially with those who disagree with him too much.

That was clearly the case with Yu.

But, said many execs at the company, Zuckerberg’s conviction that growth is key over all other concerns–about which the company today is taking the edge off by noting sunnier financial results in the internal document–has been the correct one.

Currently, Facebook is veering in on 200 million users, which represents an astounding accomplishment.

But how it is going to take those numbers and make Facebook into a revenue-rich company on par with its increasing power on the Web is the question it will face until, of course, it does.

Besides the current drama over Yu today, Facebook has also recently been embroiled in unhappiness about its recent redesign and separately, about onerous changes to its Terms of Service.

Facebook has since backtracked on both issues, likely adding to the level of pressure on Zuckerberg and top execs.

And that is not even mentioning the curse of the Winklevii–it seems the fun never stops at Facebook HQ!

On an actually more amusing note, I once nicknamed Yu “Death Cat.”

As I wrote in mid-2007:

“Like that cat named Oscar who can detect death, Yu seems to have an amazing ability to get a sweet job at the hot Web company of the moment at just the right time. Case in point: He left Yahoo as its treasurer and went to YouTube as its CFO just a month before it sold to Google for $1.6 billion, a deal in which Yu apparently played a key role. Then, on his way to a spot as a junior partner at also-hot VC firm Sequoia Capital, he grabbed the Facebook CFO job in July. I say we watch where Yu goes and follow stealthily behind so as not to be detected.”

It’s more than likely Yu will pop up again soon in Silicon Valley in another prominent CFO job or as a venture investor. Although, after today’s events, this digital cat has definitely lost one life.

Besides the more massive management reorganization that new Yahoo CEO Carol Bartz could announce this week, as BoomTown reported on Friday, the Internet company’s powerful media arm might also see a drastic shift in management structure even sooner.

According to several sources inside the company, U.S. Audience SVP Jeff Dossett (pictured here) has been working on the changes for a while, part of an overall change in how Yahoo (YHOO) makes and delivers content. The new organization could be announced this week too.

Under a plan being considered, the media unit will be split into three parts: Vertical programming, network programming and search monetization.

It is not clear under this new set-up if Yahoo will keep its more traditional structure of having powerful general managers, each in charge of its big properties.

But that seems likely to be scaled back, at the very least, since the shift in management comes after some major recent changes in the way content is made, as was also reported here last week.

Already, the media group’s product development for all its major properties–such as News, Sports and Finance–is set to be moved to a central global product development organization at Yahoo’s HQ in Sunnyvale, Calif.

Until now, such development has been mostly done by individual media properties, many of which are located down south, in Santa Monica.

The argument for the shift posits that centralizing the product development of a Yahoo media offering drives efficiencies, saves money, eliminates redundancies and accelerates growth across the world.

Those who do not like the idea think it is wrong to separate the development of a product from the programming because the two are intricately dependent and need to be tweaked delicately.

Dossett will remain overall head of media efforts, but there is a lot of speculation inside the group about who will head the three new parts of media unit. But that is still being worked out by Dossett and his boss, U.S. head Hilary Schneider, and is still not decided.

But several inside sources said that vertical programming is probably a lock to roll up under current Sports GM Jimmy Pitaro.

Former “60 Minutes” producer and News GM Neeraj Khemlani seems be the most likely candidate to head network programming, but that is not yet complete.

And Tim Mayer–who is now VP of search monetization and distribution–would probably remain in his job, with perhaps even more monetization duties added.

Ben Ling–the high-profile Facebook platform exec who came from Google less than a year ago and then up and left the social-networking site earlier this week–is about to head back to Google, this time taking a job leading monetization efforts at YouTube, according to several sources.

On Tuesday, BoomTown reported that Ling (pictured here) was leaving his job at Facebook, where he has been director of platform product marketing.

At the time, Ling would not be specific as to his reasons for leaving, saying in an interview: “Facebook is a tremendous organization, and I would not leave it if it were not for a great opportunity.”

And that opportunity apparently entails returning to his previous employer, where Ling once worked on Google’s Checkout product and other e-commerce platform efforts.

Ling’s is a move that will surely spur many to rev up the Facebook-versus-Google (GOOG) stories, given that several top Google execs–such as COO Sheryl Sandberg and PR and Platform head Elliot Schrage, as well many others–have been recruited by Facebook over the last year.

Apparently, the Empire does strike back.

Interestingly, Google CEO Eric Schmidt addressed the YouTube monetization issue in an appearance on CNBC’s “Mad Money with Jim Kramer” yesterday.

Here’s a transcript of the section where they discussed YouTube:

CRAMER: LET’S SPEAK ABOUT A QUESTION THAT, AGAIN, I’M TRYING ADDRESS THE QUESTIONS HOLDING THE STOCK DOWN. YOU HAVE TREMENDOUS DOWNLOADS IN YOUTUBE ARE EXTRAORDINARY.

SCHMIDT: BUT EVENTUALLY WE’D LIKE TO MAKE MONEY OUT OF IT, BUT IF WE DON’T, THE FACT THAT SO MANY PEOPLE COME TO YOUTUBE MEANS THEY ULTIMATELY GOOGLE AND DO GOOGLE SEARCHES AND CLICK ON ADS. SO DON’T BE TOO WORRIED ABOUT ALL THAT TRAFFIC GOING TO YOUTUBE. I’D BE WORRIED IF PEOPLE WEREN’T USING YOUTUBE. SINCE IT IS AN ENORMOUS SUCCESS GLOBALLY WE KNOW WE WILL BENEFIT.

Valleywag ran an item earlier today speculating that Ling might be on his way back to the mother ship, noting he was spotted having lunch there recently.

While the Media unit has had its ups and downs over the years about exactly what it should be–such as the controversial Hollywood-esque Lloyd Braun strategy–one thing that Yahoo (YHOO) has consistently done well is to aggregate and distribute its own and others’ content.

So well, in fact, that May’s comScore monthly unique visitor numbers show that sites like Yahoo News (38.8 million), Sports (22.2 million), Finance (18.5 million), Entertainment News (12.5 million), TV (15.3 million) and Games (18.3 million) are the No. 1 destinations for their genres on the Web.

Overall, the media properties hit 70 million uniques monthly.

That’s probably a plus these days, given all the turmoil around the company in the wake of the Microsoft (MSFT) takeover bid and the ensuing proxy fight mess–coming to an annual meeting near Santa Clara soon!–with activist investor Carl Icahn.

The whole mess has thrown Yahoo’s future into question, demoralized employees and given the company a decidedly sad-sack image, in spite of all the powerful assets it has like its many media properties.

Moore (pictured here) came to Yahoo to work for Braun in mid-2005, after toiling for many years at–wait for it–Microsoft, running MSNBC, Slate and MSN.

(I met him back when he was at Microsoft, in fact, where he tended more to suits and ties and geeky glasses–and I have the picture to prove it–rather than his current hipster SoCal look.)

His portfolio grew when Braun’s other No. 2–Vince Broady–was re-orged out of his job last December, giving Moore purview over the whole Media Group.

In Yahoo’s latest reorganization, Moore now reports to U.S. head Hilary Schneider, in a move to better align its media and advertising sales.

Moore and his staff have tried a range of large and small experiments in original content, some of which have worked and some of which have not.

Interestingly, Yahoo has not abandoned its original content effort at all, doing newsy programming like political debates and even an online interview with President George Bush.

But the company seems to be settling into a pattern best exemplified by its recently launched Tech Ticker, which is a combination of Yahoo’s own inexpensively produced but well-done content and videos and that of outside contributors (AllThingsD content is featured there, for example).

So, as part of our exciting new “Meet the Yahoos: Survivors Edition” series, here’s a video where I chat with Moore about all that, ad monetization and more: