Examining the latest version of the iPhone SDK, 9to5mac found some files and strings which clearly indicates the implementation of video calls in the next iPhone 4G!
FSM EXCLUSIVE DEAL A string within the TelephonyUI file shows the very term “VideoChat” , which indicates that video calls will be managed from the same frames as the phone application.
Pretty strong evidence, i should say. But lets just hope that this is meant for the iPhone 4G, and Apple is not testing these kind of features for a future iPxxx device.