Our law library has a special zone where cell phones are allowed - just on the main floor and in the stairwell. People still are notoriously bad at being quiet though. One guy insists on exiting through the emergency only door every single day to set off the alarm. We think he's trying to prove something.
I think the worst story is the day two 3Ls were being really noisy in the main reading room - a no-cell phone, no-talking zone. A 1L who is a non-trad and did two tours of duty in Vietnam asked them to be quiet and one of them threatened to crack his skull.