Let me just start off by saying that the iPhone 3G unlock feature is not yet available in the latest Dev Team software, QuickPwn and the PwnageTool, but you are now able to jailbreak the 2.2 firmware!
It is important to note: Things have gotten a bit more complicated compared to previous releases. If you are users of first generation iPod Touches, 2G/EDGE (first generation) iPhones, factory unlocked iPhone 3G's (the kind you can buy in places like Hong Kong) or you just have no interest in software unlocking your iPhone 3G - you can use the QuickPwn tool. If you are an iPhone 3G user that is interested in unlocking, Apple has tossed a monkey wrench in the mix for you. The 2.2 firmware upgraded the baseband. This forces you to use PwnageTool (available to Mac users only at the moment) to create a custom .ipsw file that keeps the 2.1 baseband but adds in the software functionality of the 2.2 update.
Good luck to you all!