My kids are younger, so I don't understand why an 8 yr old would need a cell phone? I read your post and a number of the answers. Perhaps for extreme situations like the gymnast who is away from her mother so much I could see it. However for your average everyday kid, I don't think a cell phone is necessary.
I think part of it for me is basically is it a NECESSITY?
Kids today have so much. They take so much for granted. I think they "miss" what's important versus what they want.
In this case, your daughter will only have ONE chance to call you. Does not having a cell phone mean she can't call? Can't write? Does she need it for safety? Has there been any problem where you fear/worry for her safety?
I "get" that it's 2010. I understand that many people see it as "only $10 per month", etc. But that's not the point. In reality it's not just $10 a month. It's the cost of the phone, it's adding them to the plan, it's any additional fees incurred (monthly per chance), and then all the "monitoring".
I think your daughter will be fine at summer camp. Have her write you letters, and save them for her scrapbook. My mom showed me mine, they're hysterical! Send your daughter a letter, maybe a new magazine, etc. NOTHING can replace care packages or letters from mom.
Save your money. Let your daughter go and have fun. She doesn't need a phone. And neither do you. She'll be just fine - 8, and phoneless.