My son knows all about MMA also, as do his friends. I guess it might still depend on where you live but we are getting quite a bit of exposure to the sport here in south Florida. I see daily commercials on local TV about a school here that specializes in MMA and I have a few friends that are pretty active in the sport.
One guy I know has actually rolled with Royce Gracie at the school he goes to in Stuart, Fl. He's got a photo of himself and friend with Royce too. It isn't one of the Gracie family schools but he comes to where my friend trains on occasion because he's a good friend of the owner.
I think it's only a matter of time before the sport gains a much larger presence than currently exsists overall, but here where I live the sport is already very well known and quite popular.