Here's an article (and a press release with a podcast) from a few days ago about an IT security company's experiment where it posted a fake profile, sent out 200 friend requests, and was friended by 82 users (41% success rate).
One of the differences between MySpace and Facebook is that users on the latter seem to disclose more of their personal information, but this information is behind the wall that you can break by friending them (or having them install a third-party application on their profiles). This great data-mining potential must have inspired the conspiracy theory that it is the CIA that is pulling the strings behind the company.
