A longtime Microsoft employee who plays an important role in the company’s advertising department is leaving the organization, according to a new report.  Then here’s the detail that may make his departure especially embarrassing for other execs in Redmond: Alex Gounares is heading to AOL.

Gounares has been with Microsoft since 1993, working on products like Internet Explorer, Windows, Microsoft Office, and the Microsoft Tablet PC as he rose through the ranks.  Gounares worked on Microsoft Virtual Earth and Windows Live SkyDrive, and acted as a technology assistant to Bill Gates for three years, too.

As for what he’s doing right now, Gounares holds the title "Corporate Vice President, Advertising Research and Development," and his official Microsoft bio says he’s "responsible for leading the engineering efforts for Microsoft Corp.’s digital advertising products."

With the culmination of the Microsoft-Yahoo deal approaching, this looks like an especially inconvenient time for Gounares to leave, then.  And it should hardly need to be said that Microsoft would like to have a better reputation than AOL.

Still, Kara Swisher, who’s pretty much always right about these things, wrote, "According to sources close to the situation, AOL has hired Alex Gounares as its CTO."