The iPhone Dev Team has released Ultrasn0w which will let you use your iPhone 3G with any mobile phone carrier, in order to use it you will need to jailbreak you iPhone 3G with redsn0w or the Pwnage tool, and then follow the instructions below.
Ultrasn0w for iPhone 3G is ready!
1. Ensure you have upgraded to iPhone OS 3.0
2. Jailbreak your iPhone 3G using redsn0w or PwnageTool (this will also install Cydia/Icy)
3. Run Cydia or Icy
4. Please add the repo repo666.ultrasn0w.com to Cydia or icy
5. Search for ‘ultrasn0w’ in cydia or icy and install ultrasn0w
6. Reboot your iPhone 3G
7. T-Mobile USA users should disable 3G before using ultrasn0w
Head on over to the iPhone Dev Teams website for more details
Update 3rd July 2009
The iPhone 3GS Jailbreak has been released, full details below.
Update 6th July 2009
There is now a Mac version of purplera1n available.
Update 8th July 2009
The iPhone Dev Team have now released the latest version of redsn0w which works with the iPhone 3GS.
Update 14th July 2009
There is now another iPhone 3GS unlock available which was developed by George Hotz
Update 16th July 2009
The iPhone Dev Team has released a new version of Ultrasn0w, you will need to jailbreak your iPhone or iPhone 3GS with Redsn0w first.
Update 10th September 2009
Apple has released a new version of the iPhone OS, version 3.1
Update 3rd October 2009
Update 12th October 2009
George Hotz has released his Blackra1n Jailbreak for iPhone OS 3.1.2
Update 13th October 2009
The iPhone Dev Team have released PwnageTool 3.1.4 for Mac OS X
Update 22nd January 2010
Details have been leaked of the latest version of Apple’s iPhone OS 4.0, you can find out more at the following link.