The departure of Dave Karnstedt, who took over last year when longtime Yahoo ad sales exec Wenda Millard left Yahoo in the first of many controversial partings, has been long rumored internally.

(In fact, I have driven one of Yahoo’s PR people crazy in recent months trying to verify a persistent tip I had been getting that he was headed out the door.)

Karnstedt will be joining Redpoint Ventures, a Silicon Valley venture firm, as an executive-in-residence.

And, in a rejiggering and addition of duties at Yahoo (YHOO), Karnstedt’s job and more is going to Joanne Bradford (pictured here), a longtime and well-known Microsoft (MSFT) exec who decamped from the software giant to helm national ad sales at trendy ad services start-up Spot Runner just six months ago.

There have been rumors swirling that Bradford was unhappy at the smaller company after working at the giant Microsoft.

She was EVP of National Marketing Services, focused on national advertisers, for Spot Runner, joining in a high-profile move in March. Previous to Spot Runner, Bradford was a VP and chief media officer of MSN Media Network, and had worked at BusinessWeek before that.

In any case, the move will be seen as a blow to Spot Runner, which recently did some unusual layoffs, despite receiving a large slug of cash from investors.

(Here is a post and video I did on a recent trip to Spot Runner, including an interview with its CEO Nick Grouf.)

“I am going back to my entrepreneurial, build-something roots,” Bradford told me at the time she joined Spot Runner. “There is such inefficiency in buying and selling of advertising and someone has to solve that, both for big companies and small ones.”

Well, welcome to Yahoo, Joanne, which could use a little efficiency in its buying and selling of ad sales!

Seriously, Bradford will now will take over as SVP of U.S. revenue and market development at Yahoo at a very dicey time.

Besides facing a withering U.S. economy, a weakened stock price after the takeover attempt by Microsoft and ensuing mess related to it, it was revealed that the Justice Department might block the deal Yahoo recently struck to outsource some of its ad sales to Google (GOOG).

Yahoo said that in this newly created role Bradford will oversee sales, market development for advertisers, small business and HotJobs. She will report to Hilary Schneider, EVP of Yahoo’s U.S unit.

Karnstedt, whom I interviewed when he first took over ad sales a little more than a year ago, is leaving to pursue other opportunities.

In Silicon Valley, that means the inevitable stop at a VC firm. Hence, Redpoint!

Interestingly, he joins former Ask.com head Jim Lanzone at Redpoint, while former Yahoo execs Jeff Weiner (Accel Partners and Benchmark Capital) and David Goldberg (Benchmark) also landed cushy EIR gigs after leaving Yahoo.

Karnstedt had been SVP of U.S. sales at Yahoo and had apparently resigned from the company earlier this summer (thanks for not confirming that when I asked so many times, Yahoo!)

With Yahoo seven years, he was charged with the difficult task of integrating Yahoo’s search, display, Blue Lithium and Right Media sales teams.

And while Karnstedt was well liked, many complained that the longtime online ad techie was not enough of a gregarious and schmoozy ad sales exec, with deep relationships on Madison Avenue, as Millard–and Bradford–surely are.

As I wrote in Aug. 2007, after an interview with him at Yahoo’s New York offices:

I made the point to Dave (he is the kind of guy you can call Dave, as you can see pictured here) that an ad guy needs to sell himself, but to no avail, so we press on in text. Nonetheless, let me set the visual scene:

Nicest guy you ever want to meet walks into nondescript room, wearing khaki-oxford-jacket Internet uniform 101. Declares Yahoo is going to kick some advertising butt in the nicest possible way. It is revealed this nice guy has been around the Web block for quite a while. Much chitter-chatter ensues. Cut to my clear-as-Fiji-water observation that nice guy, as nice as he is, has his work cut out for him.”

And now, more than ever in Yahoo’s key ad market, so does Bradford.

Lanzone had been at the company, which is owned by Barry Diller’s InteractiveCorp (IACI), for more than a half-dozen years, before stepping down in January in a management reshuffle at the company that put Match.com CEO Jim Safka at the top of Ask.

At the time, Diller praised Lanzone copiously in a statement, but noted that “these changes are intended to strengthen and streamline the operating structure at IAC, both leading up to our intended spinoffs, and beyond.”

For those not following IAC’s tribulations of late, Diller is currently embroiled in a vitriolic fight over control of the company with one of its biggest shareholders, Liberty Media, and its voluble leader John Malone.

That’s no longer Lanzone’s problem, although he remains a consultant to Ask for a little while longer and is also an entrepreneur-in-residence at Redpoint Ventures. He told BoomTown that he is still trying to figure out what to do next, but wants to remain on the product side of the consumer Internet business.

I like Lanzone a lot, especially given the more innovative and even aggressive efforts Ask has made to gain ground and try to put a dent in Google’s market share in recent years, laudable efforts a larger player like Yahoo might have been trying as hard.

While we despised the high-concept Kato Kaelin ads (see it once again posted below the Lanzone video to see why) Ask used this summer, BoomTown does not blame Lanzone for them–paging Barry Diller! All is forgiven anyway, since they were junked.

In any case, here is a video interview with Lanzone done yesterday, in which we talked about where search was headed: