Go ahead and follow this if you have a jailbroken iPhone 3G (Firmware below 2.2.1) and don’t want to mess around with the unlocking tools for 2.2.1 firmware.
Follow the following steps for both Windows and Mac Operating systems :
1) 2.2.1 Firmware from Apple iPhone 3G updates the baseband to 2.30 disabling the software unlock.
2) Make sure you have jailbroken your iPhone 3G Firmware below 2.2.1 using QuickPwn 2.2.
3) Now,if you have access to a Mac, feel free to download Pwnage 2.2.5 and build a custom firmware. Windows users might want …

Such a wonderful feat, a blessing for all those who accidentally updated their iPhones to 2.2 (2.28 baseband). Dev Team hinted a 2.28 unlock in a screenshot released today boasting the ever popular 2.28 baseband unlock. Please STOP buying x-SIMs from China and look out for the real deal on Cydia : today (Dec 31st) at 11:59 PM EST. All the iPhones in the world released to date are unlockable via a software means and please refrain from buying software unlock from any website since Dev Team intends it to …

iPhone 3G Unlock (codename : yellowsn0w) is finally ready for general consumption with an anticipated release date of December 25 ~ 31 (Christmas — > New Year’s eve!). It is currently undergoing idiot proof GUI packaging for the total noobs! However, those users who accidentally upgraded to 2.2 firmware from iTunes have no other choice but to resort to x-Sim solutions or a possible baseband downgrade from 2.28 to 2.11 (hopefully).
Great job iPhone Dev Team, you really rock the iPhone world and Apple likes it too, not sure about ATT …