At my school, students can use technology freely: cell phones in the classroom, iPads, any kind of technology. Many teachers were sceptical at first, but I really enjoy the freedom and sense of 'adult-responsibility' that it gives the students. Students using the phones inappropriately in class is rarely a problem, as they perceive their usage as a privilege and respect the guidelines for usage.
I love the fact that the students can put their headphones on when they are working independently (they're only allowed to keep in one earbud so they can still hear the teacher if needed). For many of my students getting to listen to music in class off their iPhone helps them block out other distractions.
This was the first year for my campus to go to an 'open technology' policy, but it has been relatively trouble-free and the benefits have definitely outweighed the negatives.