Every summer camp I went to as a kid had D&D as an informal activity. Typically one of the most enthusiastic / geeky counselors was the DM, although sometimes the campers DM'd themselves (er, you know what I mean).
This was either before the "D&D is evil!" scare, or concurrent, but no one cared about that. (My memory is a little fuzzy.) I think the camp administrators were more worried about whether any campers would drown in the swimming pool, or set the woods ablaze while building campfires, than they were if we pretended to be elves fighting dragons.