Both of my daughters have cell phones. DD18 got hers when she was 14, and DD13 got hers for her 13th birthday. I think in a few years, as the age creeps down, most kids will probably have cell phones by the middle elementary grades, but my girls were in the middle as far as getting their phones - some had them a year or so before they did, and some didn't get them until high school.
I'm totally in favor of them having their own phones. It's great to be able to get in touch with them whenever I want to, and to know that we can have a private conversation. Maybe I already know that my daughter is to be picked up at 4pm from school, but what I really want to know is how she and her best friend resolved the squabble they were having yesterday. Maybe I want to ask her something that she doesn't want to answer standing in front of the school secretary.
I don't have a problem with another parent making that decision for their own child, but I'm getting a little tired of parents who still see this is a "moral" issue, or as a "good" or "bad" parenting issue. A phone is just a phone. It's usually 10 bucks a month on a family plan, and calls are free to callers in your network. The cost of the original phone varies, but it isn't out of line with any other small electronic you might buy a child. I'll bet a Leapster is more expensive than a cell phone. As long as you set some rules, and remember that you can change the plan or the circuamstances, I don't see any problem with cell phones for kids, at whatever age you decide to let them have one.
I also don't have any problem with my kids using their phones to chat. I don't want them using my house phone for as much talking as they do!! I had a second "teenage" line that I'm getting ready to drop because everyone calls them on their cell phones now. I just bought a big enough plan to allow for everyone to get the minutes they normally use.