Considering this, how can I help him interact with other programmers at a similar skill level? Only a few of his friends from school or other activities also know how to program, none very well. We are not aware of any teachers or adults in his school or other outside activities who are programmers.
He has already made plenty of acquaintances on Stack Overflow and other programming-related SE sites (and chat), but he wants more of a way to actually meet people in person that he can relate to, socialize with, etc. in order to learn and grow.
note: I am actually the child, not the parent, in this scenario, but questions from a child's point of view seem to be on-topic as per meta. Nevertheless, I have posed this question as if I were the parent. This is also related to this recent question, but not asking the same thing.