I had this thought while reading dok's blog but I figure it was tangential to the main point of his post and figured it would be better to post here than as a comment there:
When I was in school, my school district decided to split the players into three leagues. The bulk of students remained in regular classes while those who struggled were put into remedial classes and those who excelled were put into accelerated classes.
This started as early as 2nd grade when students were bused from several neighboring schools to form a single class once or twice a week. At the junior high and high school levels, when these students all fed into the same school, they comprised whole classes along the accelerated learning tracks.
I remember hearing that someone was challenging the school district's ability to separate gifted students out of normal classrooms at the elementary level when I left for college but I see that the program is still up and running (and actually expanded).