The iPhone Dev Team has finally released the utility needed to unlock the iPhone 3G under iPhone OS 3.0, which will allow current users in illegitimate carriers to upgrade to the latest version of the iPhone OS, which brings about over 100 new features.
The new ultrasn0w utility is available for download through Cydia and Icy software repositories, which are both installed during the process of jailbreaking. To jailbreak your iPhone 3G running 3.0 OS you need either the Pwnage tool (Mac OS only) or the redsn0w utility, which was already released by the iPhone Dev Team 3 days ago.