They are having kids keep their phones in their lockers all day where I work. It's only the second day, but from what I gather it isn't going too well. As the tech guy I always get annoyed when teachers try to have the tech department solve what is largely a classroom management issue. Me blocking a site isn't going to make them suddenly not be bored in your class...
RE: My Students Are Addicted to Their Cellphones (and Water is Wet)