Google just announced that they will start a limited Beta test of demographic targeting for USA and UK advertisers. It looks like they are building on their deal with MySpace by getting anonymized data from their "social networking sites" partners (as well as others, perhaps) and using that to serve or avoid those users.

With Google's stock tanking over the last few months, maybe this is the shot in the arm they need to get people excited and increase the amount of money they can earn from each impression.