I very much hope that the camera will be able to be used by skype, ect. and will not be tied into ichat as even the people I know who use macs use skype over ichat
I guarantee you that 99.9 percent of the new iPhone users will use the front face camera feature for the simple fact that people love to take pictures of themselves.
I don't think it would make, incredible difference. But I would use a front facing camera, mainly for Video-Chats. It will be way more convenient to talk to someone ( GF, Wife, Kids etc) without having to carry a heavy laptop or sit awkwardly in front of a desk. It would be way easier to just carry a small phone and walk about? Wouldn't it?