At Web 2.0 AT&T Mobility President and CEO Ralph De La Vega announced that AT&T is working with Apple to officially release iPhone tethering "soon." Tethering allows another computer (i.e. a notebook) to piggyback on a phone's 3G Internet connection.
It will be interesting to see what AT&T charges for iPhone tethering – they charge US$10 per month on their other smartphones. I hope that it's not too expensive otherwise people might opt to tether for free.