First, check out some great websites like the American Camp Association for very informative information on sending your child to camp. They have good tips for first-time-camper parents!
Second, as a camp director myself and parent of two camp-going kids, my questions back to you would be, is your son worried about camp, or are you worried about sending him? Does he have any friends who are going to camp at the same time? How long will he be gone?
Sometimes the answers to these questions will help drive your actions when it comes to sending him off. For example, if it's you who is worried, try not to relay this feeling to your son- he needs your enthusiasm and support as he heads off on this adventure. =) (Easier said than done, for some!)
Generally speaking, the more information you can get ahead of time about what a typical day will be like, what items to bring, how you can communicate with your child, how homesickness or discipline issues are handled, what the staff qualifications and supervision ratios are, what your child will be learning/doing, etc., the more comfortable you and your son will feel.
Attending any information sessions, meeting other kids who will be attending camp at the same time, and talking with parents whose kids have gone to camp in the past are also helpful.
I think your son is in for the experience of a lifetime! Camp is a wonderful place to make lifelong friends, learn many new things, become more independent and confident, and have a lot of fun!! Good luck!