In addition, Whitten also announced Avatar Awardables. Awardables, as their name implies, are articles of clothing that can be awarded by Xbox 360 games for completing certain tasks. "I think you're going to see a ton of new content that comes from that," said Whitten. The apparel won't be limited to things like shirts and shoes either, as the ODST Avatar above illustrates, it's conceivable we could see little Alan Wakes and Raidens running all over Xbox Live soon.
Whitten didn't announce any release date for Awardables or the Avatar Marketplace, but given the ODST apparel, we'd say Fall 2009 is a good bet.

