According to several sources, Yahoo’s SVP of U.S. Revenue and Market Development Joanne Bradford (pictured here) is planning on leaving the Internet giant to take a new position as chief revenue officer of online content upstart Demand Media.

The surprise move is sure to have reverberations throughout the online advertising arena, but more so at Yahoo (YHOO), where Bradford’s job encompasses a wide range of key revenue-generating duties.

She has also been tapped as one of the execs to play a key role in the recently approved search and online ad partnership with Microsoft (MSFT).

Yahoo declined to comment. BoomTown has also contacted Demand and is awaiting comment.

Bradford had actually once been a Microsoft exec, serving as VP and chief media officer of MSN Media Network. She had worked at BusinessWeek before that.

Bradford came to Yahoo in the fall of 2008, at the tail end of the tenure of Co-founder Jerry Yang, who stepped in as CEO after the previous CEO Terry Semel departed.

Immediately previous to her job at Yahoo, she had been helming national ad sales at then-trendy Los Angeles-based ad services company Spot Runner.

Demand will be her second time going from a large company to more of a start-up.

But–unlike the troubled Spot Runner where Bradford worked for only six months–Demand has been on a growth tear of late with a social media strategy that is also being pursued by AOL (AOL) and others.

It owns heavily trafficked sites, such as how-to juggernaut eHow and the health- and fitness-focused Livestrong.com, putting Demand in the list of the top 20 Web properties.

It reportedly has about $200 million in annual revenue–mostly from advertising, but also from a domain registration business–and is profitable with several hundred employees.

The Santa Monica, Calif.-based company is headed by serial entrepreneur Richard Rosenblatt (pictured here), former chairman of Intermix Media. Intermix was the parent company of MySpace, which was sold to News Corp. (NWS).

Armed with an astonishing $355 million in funding from a range of prominent investors, he has been trying to fight some mainstream media depictions of his social media content company, especially one report that called Demand a “content mill.”

Via its Demand Studios, the company uses an army of freelancers to produce all kinds of content for its sites and others, using a complex automated system, but which also includes vetting and editing.

In fact, irked at the characterization of Demand as a content spammer, Rosenblatt even issued a manifesto for Demand in January.

“There has been so much misinformation about our model and what we actually do, that I thought it was a good idea for our company and those who work for us to lay out our principles,” said Rosenblatt in an interview with me at the time. “We are so different from traditional journalism, which I have nothing but admiration for, so it was time to make people understand that.”

The role of Demand Media, said Rosenblatt, was to help readers solve problems, laugh and get good advice, while figuring out how to create a profitable media business in the digital age.

(Walt Mossberg and I have invited Rosenblatt to share the stage at the eighth D: All Things Digital conference this June, along with former Wall Street Journal editor Paul Steiger, who is trying to save investigative journalism at a nonprofit called ProPublica, to talk about it all.)

If Rosenblatt is successful, Demand appears to be aiming for an IPO or merger with another company. Ironically, Demand has also been eyed by Yahoo in the past, as a possible acquisition.

Nabbing a top Web exec like Bradford from Yahoo is obviously a definite step in raising the stakes for Demand with big, established advertisers.

That’s because Bradford is well-regarded in the industry and is a prominent player. She recently signed a high-profile deal with Hollywood producer Ben Silverman to create premium content for Yahoo.

Bradford’s departure will be seen, both internally and externally, as a definite blow to turnaround efforts by CEO Carol Bartz. Bradford currently reports to Hilary Schneider, EVP of Yahoo’s U.S unit.

My reporting does not indicate that Yahoo’s top brass know about Bradford’s expected move, so it is not clear who would replace her at the Silicon Valley icon, which has been hard hit by an exodus of talent over the last two years.

Internal candidates could include 11-year Yahoo veteran Mitch Spolan, VP of North American sales, or Seth Dallaire, a former Microsoft exec whom Bradford brought to the company last fall as VP of mid-market sales, a newly-created role responsible for all mid-market sales efforts across search and display advertising.

More to come, obviously…

On one of my many trips to Los Angeles (what can I say? I like to hang where LoRo* hangs), I dropped in to see Nick Grouf of Spot Runner.

As many might know, Spot Runner is an online-offline ad agency play that has gotten big funding and even bigger hype of late.

We’ll see how that goes. But Spot Runner actually seems to be tackling an underserved (and unexciting) market of local and national clients in need of cheap online ad solutions married to more traditional marketing venues to boost revenue.

Here’s my video interview with Grouf at Spot Runner’s offices on Wilshire Boulevard:

I met Grouf many years ago when he–along with Spot Runner partner David Waxman–founded PeoplePC and Firefly Networks.

Grouf sold the struggling PeoplePC–which hawked computers bundled with an online service–to Earthlink (ELNK) in 2002 for $10 million and assumption of $35 million in liabilities, in a Web 1.0 meltdown deal that followed a disastrous IPO.

He then started working for the Presidential campaign of Sen. John Kerry, helping figure out how to best and most cheaply place critical television ads–crunching all sorts of data about lots and lots of neighborhoods and towns and cities nationwide to figure it out.

What Grouf figured out, though, was that a system for doing so was nonexistent.

That experience turned into Spot Runner, which is essentially a do-it-yourself model that tries to iron out inefficiencies in the buying and selling of advertising and bridge the gap between the traditional and online ad markets.

Offering cheap ad templates, clients can make and place low-cost television and radio ads for small and national businesses, as well as political campaigns, and get analytics about the impact of the ads. Some ads cost as low as $500.

Spot Runner got a pile of cash to try to do that better, recently nabbing $51 million in funding to add to the $60 million already raised.

Investors include international media giants Daily Mail and General Trust (DMGT.L) and Grupo Televisa (TV), investment company Legg Mason Capital Management (LM) and luxury conglomerate Groupe Arnault/LVMH (MC.PA).

Spot Runner’s previous investors are Allen & Company, Battery Ventures, Comerica Bank (CMA), Lachlan Murdoch, Vivi Nevo, Capital Research and Management, CBS (CBS), Index Ventures, Interpublic Group (IPG), Tudor Investment Corporation and WPP.

Its board includes Index’s Danny Rimer and former AOL exec Bob Pittman.

All that money has given Spot Runner an eye-popping valuation upwards of $500 million.

This is its biggest burden, I think, setting expectations very high for what is still a little start-up.

And while there are rumors of both Microsoft and Google, as well as Comcast, being interested in acquiring the company, Grouf dismisses the speculation.

He says Spot Runner is more intent on using the money raised to buy companies and improve its offerings.

For example, it recently bought Weblistic, a local search listings creator, and hired former Microsoft exec Joanne Bradford.

Bradford, who was a VP and chief media officer of MSN Media Network, is executive vice president of National Marketing Services at Spot Runner, focusing on getting national advertisers to also think small and targeted.

Who knows whether the company will be able to overcome its hype, but time (and money) will tell.

(*And a free D6 bag for anyone who correctly identifies who I am referring to here, either by sending in a comment or an email to me at kara@allthingsd.com.)