I just found this little project called Month of MySpace Bugs. This should be interesting to keep an eye on. As they state, they are only picking on MySpace (they could have found similar problems in any of the poorly crafted social networking sites) because they are trying to get attention, MySpace is extremely popular to get them even more attention, and that MySpace is “notoriously dickish” in response to security issues.
Starting on April 1, they will release one MySpace hack a day. Most will center on XSS attacks and they invite anyone to send in a hack as long as you have a proof of concept. It sounds pretty light hearted and looks to be half goof, half public beating.