I've added a few MU basketball players on facebook. I don't know any personally, but I find it interesting to see what kind of person they are. You can't read much into what they write, but I do think you can get a picture of their personality over time. If you're expecting to find actual news on there, though, you're probably going to be disappointed (although the Ratliffe commitment did break first on Phil Pressey's facebook page).
None of the Mizzou coaches have a ban on facebook/twitter, although I do know Kim English put a ban on himself shortly after the season started. He's extremely active on twitter and took it down because he thought it might be a distraction.