Via The Verge who spotted the news on iDevice, this news arrives:
An apparently new warning message, first spotted by iDevice, shows up if users try to disable 3G data while on a FaceTime call. “Disabling 3G may end FaceTime,” it reads. “Are you sure you want to disable 3G?” Since the call is still running over Wi-Fi, disabling it does nothing, but re-enabling it afterwards gives a similar message. “Enabling 3G will end your phone call. Are you sure you want to enable 3G?”
Video calling over 3G on Facetime has got to be one of the most requested features we’ve clamored for since its debut. Looks like it’s just waiting in the wings.