I think the preschool is a great idea, since GTness tends to run in families. You've got a better shot at finding a group of true peers in that room than you would in the world at large, I would think.
My only caveat would be that it shouldn't be a hothousing school. Let the kids have the opportunity to read and do multiplication if they want to, but let them play with blocks or ride trikes if they'd rather. More opportunities are always better than fewer, but outside pressure to do academic work at to young an age is not necessary or healthy. Follow the kids' leads.
I know a high-pressure preschool is not where you were going with this, Grinity, but I could see it being turned into something high-pressure...
