Buried in the announcement of iPhone OS 3.0 was the intent to support 3G tethering, i.e. connecting your iPhone to a laptop to turn it into a high-falutin' modem. In the following Q&A, Scott Forstall of Apple clarified the tethering issue thusly:
Q: Where do you stand on tethering?
A: There's two pieces needed to support that: client side and working
with carriers. We're absolutely supporting tethering in the client side
in iPhone 3.0,
but we're working with carriers around the world to see when they can
add tethering support on their networks. But we are building that
support into iPhone 3.0.
In other words, the buck's been passed to AT&T with a "not my job, maaaan" handwave. Then again, if you have a jailbroken iPhone or G1 handy, you can cruft together a tethering system right now.