First let me say before you flame me or give me "bad karma" on reddit.com, that I support Paul Graham's "Summer Founders" program. I like to think that I'm not just bandying the verb "support" when I write this, but that I actually tangibly support the program. After all, I'm a reddit reader ;) Furthermore, I've promoted kiko on this site.
But I really have to question whether, as he claims, Mr Graham has tangibly (there's that word again) tested his hypothesis about which he most recently has written in his essay "What I Did This Summer" at http://www.paulgraham.com/sfp.html, which, by the way, I discovered through reddit. That hypothesis being, and I quote "that success in a startup depends mainly on how smart and energetic you are, and much less on how old you are or how much business experience you have."
Mr Graham immediately goes on to state that "the results so far bear this out. The 2005 summer founders ranged in age from 18 to 28 (average 23), and there is no correlation between their ages and how well they're doing." Well I'm glad he said "so far" because, even with my rudimentary statistics knowledge, I know that his sample "so far" has been nowhere near large and varied enough to really test his hypothesis.
Now there is going to be the "Winters Founders" program and so the sample size will increase. But personally I have doubts as to whether it will become more varied. From everything Mr Graham has written so far, his programs definitely seem slanted towards attracting young talent. That of course is his prerogative, and presents a great opportunity for these youngsters, which I gather is the real point, as opposed to proving some theory. Get some subjects in their 30's and 40's into the sample, and I'll take his hypothesis more seriously.