Someone posted this comment on how FaceTime works..
"Speaking of FaceTime, Jobs mentioned that it's only available on wi-fi until U.S. carriers improve their bandwidth and reliability. But at the same time, he was clear that FaceTime is strictly a service available between two iPhone 4s -- Macs with an integral camera and iChat are out of luck. It turns out this isn't some arbitrary limitation, though, because FaceTime requires a telephone connection despite its reliance on wi-fi.
Here's how it works: An iPhone 4 user calls a fellow iPhone 4 owner over GMS. Once the connection is made, both callers press a FaceTime icon, which activates the camera and causes the connection to shift entirely to wi-fi. For the time being, iPhones are the only Apple devices capable of both phone calls and wireless connections, and the iPhone 4 is the only model with a front-facing camera, meaning that FaceTime is limited to iPhone 4 out of necessity. No doubt that will change over time, and chances are good that non-Apple devices will make use of the tech as well since Apple has declared it an open standard.
My hope is that the open nature of FaceTime means that App developers will be able to incorporate it into games and other software. I can't actually imagine how it would be integrated into a game, but the possibility is intriguing nevertheless. But even if FaceTime remains strictly a "welcome to the future" version of standard telephone, its inclusion (and the various improvements to the hardware design, to say nothing of the improved battery life) makes iPhone 4 a much more impressive update to the device than last year's 3GS."
My comment - its too complicated and it needs other iPhone 4 to communicate.... I don't think this feature will fly....