Arnold Kling points to evidence that Gifted-and-Talented programs don't make any difference for students, and offers the following thoughts:
G&T programs are one of my pet peeves. I believe the following about them:
1. The main reason we have them is because parents love it when their kids are placed in them. It is a huge status thing for parents. G&T programs could have negative effectiveness and still be enormously popular.
2. Either you believe your bright kids should experience going to class with students who are not so bright, or you don't. If you don't, then pay for private school. G&T allows you to send your kids to private school while claiming they are still in public school.
I find it maddening how many upper middle class parents energetically "support public education" against the depredations of vouchers and other reforms, while moving their own children into better school districts or better programs. Especially parents in Manhattan and a few areas of Brooklyn who proudly note that their experience shows how great public education is, while failing to note that their schools work because these comparatively affluent parents with a great deal of social and political capital fight like hell to divert as many resources as possible--including the best teachers--into a handful of schools in affluent areas. New York's famed magnet schools are a big part of this dramatic inequality, and yet the middle class parents who sent their kids there somehow thought their kids had more in common with the kids at Samuel J. Tilden than at Dalton.