I remember they did that at Jr.High last year. They did that with tons of people for Ipods and other crap like that. What pissed a lot of people off, was the principals were seen looking through the phone, such as adress books, texts, all that good stuff.
Now in highschool, I am pretty sure that you can just pick it up at the end of the day. Although, the only person I have seen enforce this law is our assistant principal. Other teachers, everyone has their phones out looking at them, texting.