After a decade at Microsoft, Lisa Utzschneider is leaving her post as GM, sales, for the Microsoft Digital Advertising Solutions group, to join and build up Amazon.com’s (NSDQ: AMZN)  ad business, NYP reported, citing emails by unidentified sources discussing her exit. Amazon, which hasn’t made any announcements of Utzschneider’s hire, is said to have named her to the post of SVP, national ad sales. The hiring suggests that Amazon wants to make online advertising a bigger part of its overall business. If so, the company’s picked a tough time to ramp up these efforts, with internet ad revenue growth slowing. But with the wider economy on shaky ground, perhaps Amazon feels that it must try to exploit any other chance to make money online.

Stifel Nicolaus analyst Scott Devitt told NYP that Amazon has been more aggressive about letting third-party entities advertise within its site. Amazon already sells display ad space on its web properties, which include movie site IMDB, Askville.com and digital camera reviews site DPreview.com.

As for Microsoft (NSDQ: MSFT), Utzschneider’s departure represents another high-level hole to fill on its ad side, following Kevin Johnson’s decision to leave as president of its Platforms and Services Division in July to head up gearmaker Juniper Networks. Before that, Joanne Bradford left Microsoft back in March for what turned out to be a short stint at Spot Runner, though this week she decamped to go to Yahoo.