Media event set for September 9, launch likely ~10 days later.
FaceTime Over 3G Comes to Jailbroken iPhone 4s
My3G essentially tricks a user's phone into thinking it is on Wi-Fi instead of 3G, allowing users to access a number of features and types of content typically restricted to Wi-Fi connections. My3G is typically available to jailbroken iPhones via Rock Your iPhone for $3.99, but the site is currently down due to the high traffic load.
9 to 5 Mac has posted a video briefly showing off FaceTime over 3G in action.