While many people debate whether electornics are safe to use on planes, the FAA takes the regulation very seriously. Take Alec Baldwin for example, he was recently playing the incredibly popular and addicting game Words With Friends.
When the cabin door was closed, FAA regulations say you have to turn off all electronic devices. Alec Baldwin refused, and when they asked him to, he got angrier, and took his phone to the lavatory (another no-no). He became so disruptive, that they had to turn the plane around and kick him and his schweddy balls off the plane!