The general vibe I've always gotten is that it roughly breaks even, so far. Jessica and pg have both asserted this in the past, in articles or in conversation.

But, that was a year ago...and with Loopt still iterating and signing on new providers and creating new services, Xobni still growing and getting pretty monstrous press, and at least two or three other potential IPOs (or at least >$50 million acquisitions) in the making, it's definitely too early to say what kind of money YC will make. If I were an investor, there are several former YC companies that I would like a stake in, even at a valuation much higher than what YC bought in at. The average exit in the valley, according to one of the speakers at Startup School this year, happens seven years after founding. On that timescale, all of the YC companies are still very young.

Only time will tell if these young-ins have the patience to wait that long (7 years).

Who says they're "waiting"? I would think "work that long" would be a more appropriate way to put it, as merely waiting won't get a company to an exit no matter how long you wait.

Anyway, the ones that wanted a quick exit have generally already had them, or given up and gone to work for someone else. There have been five or six YC exits, so far, and all of them count as "early cheap" exits (though most of them are now "rich" by some definition of rich, they were still merely high six to low eight figure exits)...the companies that are still in business and haven't been acquired after two or three years obviously have bigger plans. In the past couple of months, I've talked to three YC companies that have had acquisition offers but have turned them down.