There was some legislation a few months back that would have blocked MySpace from libraries (or more specifically, blocked public funding from places that allow MySpace on their computers). Since we still have it available here, I'm guessing the legislation didn't pass. (I think it was a pre-election "For the children!" campain promise.)
I restrict the computers to homework or research only during after-school hours on weekdays, which the kids complain about, but if I didn't they would all spend 55 minutes of their alloted hour on MySpace, then 5 minutes researching, and complain they don't have enough time to do their homework.