My two cents (from being, and having, a kid) is that it's a little too young for photography. Get him some stuff to draw or model with, and if you must get something photographic, get a small P&S like a disposable camera. At that age it's more about learning motor skills and getting creative. As an artist and a photographer, I'm convinced that the more traditional arts are the way to go w/ that. Photography is not the same, especially the undesirable lag time between inception and finished image.
More and more I see I need to go back to my drawing and printing and take a breather on the photography because the photography aspect isn't at all the same in a creative manner. It's way too analytical. With a drawing/print/painting, spontaneity and intuition rule the day. Some of my fondest times were when I, and time, ceased to exist. For those few minutes I WAS the drawing, to use a Zen term, and there was absolutely no thinking going on at all, yet the drawing was being made, even though I wasn't really aware of that happening at the time. I was "in a zone".
As an adult, drawing is fiendishly difficult. It requires practice, practice, practice. Stop doing it for a while and you'll be back to drawing stick figures until you get your chops back. When you're a kid it's more about the joy of seeing that image get on the paper from your own hand, and it focuses the attention on the moment and reality. Drawing and other art stuff is something a child can do in a group setting too, and everybody gets to see the others work in real time. An art class w/ a non judgmental teacher would be good. Someone that would praise the results. When I began my adult career as an artist that is what I remembered back to, being in an art class at an early age and seeing an 'A' on my paper (the only subject that ever happened with), and seeing my stuff hanging on the wall w/ the other kids. I remembered the praise from my teacher, and bringing that 'A' paper back home to my folks. Stuff like that lasts a lifetime, and sets a good idea in one's head about their abilities and self worth.