I have a friend who works part time as a Dispatcher here. When I asked him how many calls they normally get from children that don't know any better than to call 911 (because they are curious or crave attention or whatever), he responded that a good 5-10% of calls were little kids without emergencies. I don't know about you guys, but I find that percentage to be huge.
Not that I'm defending these dispatchers, it is the local Dispatcher policy to return all 'prank' calls from children in order to inform the Parents. That might not necessarily be true in a larger community.
Obviously it would rock if we could have everyone who pranked called 911 be arrested or at least checked out, but I'm sure that it is not a feasible priority for the police...especially with recent budget cuts.