Well, this is interesting. Our twitter follower @chenks points out that, hidden in the metadata of a picture taken with his OS 4.0-enabled iPhone, there is a title stating that the picture came from the phone's "Back Camera." Of course, if the phone currently has a back camera, there's a possibility that it could, in the future, have a "Side Camera," or more appropriately, a "Front Camera."
We're being facetious, of course. This certainly seems like yet another hint that the next version of the iPhone (expected sometime next month) will have a front facing camera; that's not only a long-awaited feature for the iPhone faithful, but it was also seen on that lost iPhone prototype not long ago.
So, at this point, it's more or less a terribly-kept secret that the next iPhone will finally have a front facing camera. The question is: will you use it? I'd rather not have my ugly mug going out across the wires every time someone calls me, but I suppose there are a few applications (possibly including an official iChat Mobile application) where it might come in handy.