I knew someone at school who joined, but I'm not sure he ever got any real benefit from it. If you're stuck in the boondocks, or stuck in underemployment, I can see that it could be a Good Thing -- but the joining criterion is the top 2% of the population, which is actually quite a lot of people. If you go to a good university or get a good white-collar job, you're mixing with all of those people already.

One area where they could make a difference, but I don't know whether they try to, is in the education of bright children. A lot of schools, or a lot of teachers, aren't really geared up to deal with the top end -- though again that might not be apparent at the 2% level, as there'd be a bunch of 2% kids in every single school year.

Peter