FWIW, I saw that over half the attendees from the Simons summer of 2011 went to Harvard, Princeton or Yale with all the rest going to similar top schools such as MIT, Caltech or Stanford, etc. ( A few accepted prestigious scholarships from state school programs.)
I have come to the conclusion that all of these programs are pretty much on par with each other and the name of the program does not matter as much to admissions officers as what you actually do at them. The reason why the kids do well in college admissions is that the programs are pretty much looking for the same things as the colleges, so to get past their hurdles is tantamount to getting past the admissions hurdles at selective schools. Performing high-level research that leads to an award or published paper and a great research recommendation is just icing on the cake.