Well, I would argue that its possible that "small startup" could mean a wide range of things, not simply the kind of company Y Combinator tends to fund.

I would also argue that an iPhone app company is at least as likely to be a successful Y Combinator startup as just about anyone else they've funded.

It's a mistake to assume that since indie Mac software has traditionally been written by one guy with an LLC, that all iPhone software will be written that way. For one, the iPhone is a completely different market, much more akin to the iPod than the mac.