You cant unlock the iPhone 3G yet. Except with Hardware Unlocks.
The iPhone Dev team is working on an unlock, and when its out, well know here >
blog.iphone-dev.org
I say when, because its only a matter of time.
Quickpwn can be used to Jailbreak the iPhone 3G.
Winpwn and PwnageTool, can Activate & Jailbreak the iPhone 3G, and Activate, Jailbreak and Unlock the iPhone 2G (All Firmwares, including 2.0.1)
3 more days till the very expensive 3G is out here!