Hm... have any of you considered the health risks? There is a growing body of evidence that cell phone use can increase the risk of brain cancer. Children are at greater risk, because their bodies are still growing and developing.
My son didn't have a cell phone until this year -- and he's in college now. He has it ONLY to help us coordinate, and it is always turned off when he is in class.
If the cell phone is always turned off while in class -- I can find it acceptable. However, so often, even if that is the rule, it isn't the case. Then you get into a host of other problems. I think that, except in rare cases, there isn't a strong case for kids to have cell phones in k-12 schools.