This is a step by step tutorial on how to update and jailbreak/unlock your iPhone on 3.0.1 firmware. The firmware is almost the same as 3.0 except for fixing up the SMS vulnerability. The following files are needed:
3.0 Firmware IPSW
To unlock add "repo666.ultrasn0w.com" to sources in Cydia. ultrasn0w is spelled with a 0 (zero).