We're in the dog days of summer at this point -- the sun is high and hot, the beaches and swimming pools are full, and if you're a kid, the days are long and lazy. Which is probably why we've got all the kids in game lately -- as donnyman notes, when school lets out and summer is underway, the population of Azeroth seems to get much bigger during the day. Some might say that's a good thing: more people playing means more PuGs and more AH buying and selling, while others might say they don't really want more of the younger audience in the game.
I haven't had too much experience with this lately, as most of my gametime is in the evenings and on weekends, so I already see most of the school folks as I play. But I do remember the yearly migration of kids to video games -- I worked at Gamestop for about a year and a half after college, and sure enough, whenever school let out, we had more kids in the store talking about how they'd spent all day yesterday playing online.
So is it a problem for you, or have you even noticed the influx of summer visitors at all? We have to be careful not to generalize here, as while some younger folks can cause issues (either by acting like kids, or just by filling up the instance queues), there are certainly others who act very mature for their age. Some of them, especially with parental supervision, can actually make model players. So the question here is: how have you experienced the sudden rash of schoolkids?