David Ko (pictured here), head of Yahoo’s mobile division, has added the Internet giant’s vast media properties in the U.S. to his portfolio, according to several sources.

BoomTown recently reported that Ko was the likely person to take over as North American Audience head at Yahoo (YHOO), reporting to U.S. EVP Hilary Schneider.

With purview over programming and more for the main Yahoo media properties, such as News and Finance, he fills a slot left by the departure of Jeff Dossett in May.

Since then, the key Yahoo content division has been run jointly by Jimmy Pitaro, who heads Vertical Audience Experiences for Yahoo, and Tim Mayer, who is in charge of Search & Social Applications, as well as the powerful homepage of Yahoo. Both now report to Ko, who joined Yahoo in 2000, sources said.

But, in a related move, product development for mobile has moved from under Ko to CTO and EVP of Products Ari Balogh.

A similar move of Yahoo’s media properties took place earlier this year, shifting key tech development responsibility to a global product organization at Yahoo’s HQ in Sunnyvale, Calif.

Previously, as had been the case in mobile, such development had been mostly carried out by individual media properties.

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

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

But, said one source, mobile has been deemed by CEO Carol Bartz as “part of the core” at Yahoo instead of more an experimental offering as it has been viewed internally.

Thus, mobile apparently needs to be closely aligned to all product development going forward.

Ironically, one of Yahoo’s more high-profile mobile efforts, its Yahoo Go mobile software application and portal, which was launched to much fanfare at the Consumer Electronics Show in Las Vegas almost four years ago, will be shuttered Jan. 12, 2010.

Now, under Ko, Yahoo’s mobile efforts have been centered around building apps for smartphones, although that market has become increasingly dominated by players such as Apple (AAPL) with its iPhone, Google (GOOG) and its Android effort and many others.

Google also just bought an innovative mobile advertising company, AdMob, which gives it a headstart in this nascent arena.

Without its own device and a dominating strategy, Yahoo must use its Web heft to push its content into the mobile space.

Presumably, that is the thinking behind giving Yahoo’s mobile and media properties the same boss.

Ko, who has worked in a variety of areas at Yahoo, took over as SVP of Yahoo Mobile after Marco Boerries left in late February as EVP of the Connected Device Division, which now does not exist under that name.

He had run Yahoo’s mobile business in the Asia Pacific region.

According to Ko’s Yahoo bio, he previously worked at Salomon Smith Barney as a senior associate and analyst. He is a graduate of New York University’s Stern School of Business.

Ko, who lives in San Francisco with his family, the bio notes, inexplicably “enjoys reading tech blogs.”

Well, then, Dave, we hope you have enjoyed this post!

A few weeks ago, BoomTown had lunch at Microsoft’s Silicon Valley campus in Mountain View with Dan’l Lewin, the software giant’s corporate VP for strategic and emerging business development.

In other words, Microsoft’s friendly face in the Valley, in charge of its operations there, which has about 2,000 employees.

Most of them work for other Microsoft (MSFT) divisions, leaving Lewin primarily responsible for the company’s relationships with start-ups, venture capitalists and industry partners.

It has, for example, relationships with Web 2.0 players like Digg and Facebook of late (pricey friendships, but friendly nonetheless). And it bought Tellme several years ago.

But Microsoft is not much of a big acquirer and has long been portrayed as Silicon Valley’s nemesis.

But times change and that image has been slowly shifting as its hammerlock of power has lessened with the surge of important players like Google (GOOG).

Lewin attributes that to more predictability from Microsoft (translation: not coming down like the Visigoths and pummeling folks without warning).

Unlike many Microsoft execs, Lewin has worked all around the tech industry, including at Apple (AAPL), NeXT Inc. and GO.

Here’s my chat with Lewin, where we talked about all that and more: