Two things, one, why do we assume that a rounded square is a camera, and second, I find it hard to believe that Apple, the company that prides its self on design, would put a camera at the bottom of the front of the phone. If there was a second camera, it would make a lot more sense to put it at the top of the front screen, like all the nokias that have 2 cameras.
(1) because it is quite a similar size/shape as the iSight cameras embedded in many other Apple products so one can imagine that the R&D is already bought and paid for and very well understood.
(2) If you turn the thing on the side to watch video, then the camera isn't on the bottom anymore. Or someone else mentioned turning it upside down to use iChat. Or sideways the other way. Doesn't seem like much of a reach at all.
Other comments have indicated something about fingerprints, but really, I don't know that this is a big problem. Sure, for a Nikon D80 fingerprints are bad, but for a VGA-res camera, chances are you'd wipe it with your finger to clean it anyway and it wouldn't make a big difference. Try it on an iMac iSight... The quality isn't sufficiently high to matter.