My wife and I just used FaceTime on our iPhones for the first time, for a legitimate purpose. We recently moved into a new apartment and my parents who live 5 hours away have not been to visit yet. I fired up iChat tonight to call and talk to them from my 27" iMac to their 24" iMac using our webcams/microphones. On the call, they were asking how well our unpacking was proceeding, and I tried to tilt my iMac downward a bit so that they could see all of the boxes stacked up behind us still. Then I had an idea.
I snatched my iPhone 4 from my desk, called my wife's iPhone 4 and handed the phone to my wife. Telling her to stay put, I ran into the other room and grabbed her phone, answering the facetime call. My wife proceeded to hold the iPhone up to the webcam on my iMac, which my parents said they could see O.K., well enough to make out what was on the screen with reasonable detail. I then walked around the apartment with my wife's iPhone 4 giving them a mini-tour. iChat to iChat over the internet, analog from webcam to iPhone 4 screen to another iPhone 4 over wifi, from the other iPhone's rear-facing camera. And it worked.
They like the new apartment by the way.