It's been known since day one that iPhone OS 3.0 would support data tethering, and Apple took the opportunity at WWDC today
to drive the point home by saying that it'd be launching the service with 22 carrier partners in 44 countries. Of course, it's easy to have assumed that AT&T wouldn't be one of those partners, but we've been told today by a company spokesman that it will be offering tethering on the device -- it just doesn't have any announcements to make at this time. Whether that means availability will be delayed (perhaps until the 7.2Mbps upgrade
is built out) or they're just trying to hammer out pricing, we don't know, but it's a promising sign.