Awkward! As Microsoft Marketing Event Opens, Its Longtime Marketing Head Announces Surprise Retirement

Timing is everything and, sometimes, very awkward.

Today at its Redmond, Wash., campus, Microsoft is hosting a splashy online “marketing leadership summit” titled “Imagine 2011″–a gathering of top marketing execs from across the globe, most of whom are advertising clients of its online division.

Also today: Its longtime head of global marketing, Mich Mathews, announced her departure–to the surprise of many Microsoft execs here, in fact–via a report in Ad Age.

In the article, she said she had told execs at Microsoft just last night.

Mathews, who is probably Microsoft’s top woman executive, has been at the software giant for a dog’s age–22 years. (BoomTown met the sharp-witted and often pointed exec in the early 1990s, when she was in charge of the PR operations for the company.)

As SVP of Microsoft’s Central Marketing Group, Mathews oversees a $1 billion budget for Microsoft products such as Windows, Xbox , Window Phone 7 and its Bing search service.

While Microsoft will be conducting a global search for a replacement, several sources said the most obvious internal candidate for the job is Yusuf Mehdi, who is SVP for its Online Audience Business.

He leads global product management, strategic partnerships, business development and U.S. marketing execution for the unit.

Another strong internal possibility: Chris Capossela, who just left his job as SVP of the Microsoft Business division for unspecified duties around social initiatives. He had a similar job to Mehdi’s, with key marketing duties.

Attendees at the Imagine event were buzzing about the Mathews news, taking some focus off the program, which included an opening speech by CEO Steve Ballmer.

Ballmer did not mention Mathews onstage, which was a by-the-book overview of its online ad offerings.

Another sticky situation for Microsoft: The Imagine event was organized by another top woman exec at Microsoft, global ad sales head Carolyn Everson.

But, she left the company in mid-February after only six months, for essentially the same job at Microsoft partner Facebook.

Since then Microsoft and Facebook have been wrangling over the talent raid, including Microsoft even considering legal action to block the move.

(In yet another unrelated embarrassing situation–here’s an excerpt from a memoir by Microsoft co-founder Paul Allen, in which he alleges co-founder Bill Gates tried to shanghai him out of shares when he was sick with cancer.)

Like I said: Awkward!