Gifted Child Quarterly recently ran a package tackling various "myths" of gifted education. This page has a list of the short articles, with links to PDFs of each of them. They're all written by big name researchers in the field and are worth checking out.
I particularly enjoyed reading James Borland's take on the problems of specifying what percentage of the population is gifted, mostly because he weaves in the movie Spinal Tap when discussing IQ. Obviously, any scale of measuring something as varied as human intelligence is going to have some arbitrariness to it, much like the amp in Spinal Tap that is extremely cool because it goes to 11, rather than 10.
Many an advocate of gifted education has gotten caught in this argumentative trap. The problem is then when people -- acknowledging this issue -- get sucked into another logical fallacy, such as that just because something is difficult to measure it must not exist or must not exist in differing quantities. Even if we had absolutely no good way to measure intelligence, or creativity, or things like that, that wouldn't mean that some people wouldn't be better at coming up with new solutions, or solving problems, than others. The fact that relying on IQ tests as a measure of giftedness has historically excluded some bright people from programs doesn't mean that no one's gifts should be nurtured. The answer is to individualize education -- to challenge everyone to the extent of their abilities. That involves turning teachers into coaches, developing everyone's talents as best we can.