It would seem as though AT&T released a new broadband 3G card, the Sierra Wireless AirCard 881. Retailing at $149.99 with a 2 year contract, its no wonder that tethering your iPhone 3G is frowned upon. I recall reading that AT&T's excuse was that tethering created instability in their network; however, because this card also runs off of 3G and Edge, is this really the case?