I went to a New Tech High School. In my third year there was a class that allowed cell phone usage and iPods as long as you spent at least 95% of your time on task. Suddenly the whole class was many times more productive because they no longer had to be sneaky about their cell phone use. So long as they were on task, they got to use their cell phones and MP3 players. It was so effective that it quickly became a school-wide policy, with the decision to ban cell phone and MP3 usage coming down to individual teachers. The few teachers that objected to the change didn't make it past the first semester before allowing them.