Holy crap we're approaching the need for an Ask Slashdot FAQ. I feel old.

Already in place in Morris County, NJ. And BTW, there's more to it than merely "not using it or else." Kids subscribe to RSS feeds, have alarms, event-tones and other nonsense that isn't caller-to-caller. Whether legal or not I'm not arguing, whether helpful or not I can't say, but I can see the schools' side of the argument and think thousands of kids are not going to suddenly (remember to) shut off their phones before starting a school day.