Paul Graham has backpedaled from one of the initial goals of Y Combinator, funding companies with no lower-bound for the age of founders.
With the publication of this essay, http://www.paulgraham.com/mit.html, he has backpedaled from that stance because of his personal moral culpability for encouraging people to become drop-outs. So if you are seeking Y Combinator funding and are a current undergraduate, tell Paul Graham that you are dropping out to start the company regardless of whether or not he funds you.