Numerous online sources have confirmed that USB tethering, publishing video to MobileMe & Find MyiPhone are in the iPhone OS 3.0.
Tethering we knew may be included but it will depend on the carriers, to weather of not it is impletmeted.
Find MyiPhone would be very useful if you left your phone somewhere accidently, I assume it will use the aGPS, Cell Tower and WiFi triangulation to find the phone via MobileMe.
The fact that you can post video shows promising ideas for the future, however with no video recording app, unless jailbroken, this feature won’t be of much use.
Sam's Blog 