I used to think that cell phones were only for adults too. I did get my daughter her first cell phone when she was twelve. My thought was for safety issues primarily as she walked home by herself along a very busy road. There have been times that she would be nervous and she would talk to me on the phone, while walking, until she reached a place that she felt comfortable. I think she has shown great resposibility in that she had the same phone for two years with no damage and only "misplaced" it a few times, that and she doesnt really like to talk on the phone much, so she has never, and I do mean never, used all of her minutes. Now that she is going into high school, that may all change, but I know that I can get ahold of her and her me, when the need arises.
I think I would ask the kids, why they want or feel they need a cell phone and see what their reasons are. I have friends that have young kids with phones and I do think there is an age that is to young, like six or seven, unless maybe its a phone that can only call mom, dad or for help. I, personally dont think it should be used as a status or popular issue, even tho that does come into play at some point, regardless of the age of the user. I also felt that being a single parent, her having her own phone has been a posistive more than a negative addition. Good luck, hope this helps a little.