AT&T's iPhone tethering is something near and dear to my heart. In fact, I may or may not be writing this tethered to my iPhone on a train to New York City right now. We know tethering works on AT&T's network because frankly, we've been doing it using only Apple's software since the iPhone 3.0 betas have been out (and before using PDAnet). To keep tethering possible, all we've had to do is not update to 3.1 - which isn't that easy.
Tethering is really handy when travelling, or as a home back-up Internet connection when the cable/DSL is out. It works well on USB and slightly less well over Bluetooth, so long as AT&T has service in the area - which isn't always.
But AT
