Steve Jobs indicated that FaceTime wouldn't be restricted to the iPhone 4. Now while the iPod Touch can go up to iOS 4 which has the FaceTime application, it doesn't have the camera to support the function. The iPod Nano got a camera last year, which means it could be the iPod Touch's turn.
MacRumors posted a few pictures of a potential bezel for the new iPod Touch from the manufacturers of the device.These images suggest a potential camera being added to the device.
FaceTime works over Wifi and uses phone numbers, however, since the iPod Touch doesn't have calling functions, MacRumors suggests that the device will use email addresses for FaceTime.