Dev Team’s unlock tool Ultrasn0w v1.2.4 is out there which is now supportive for iOS 5. User can unlock iOS 5 on iPhone 4, and iPhone 3GS whereas iPhone 3G with old basebands is also compatible for the latest Ultrasn0w.
Ultrasn0w v 1.2.4 Supported Basebands
- iPhone 3G/3GS: 04.26.08, 05.11.07, 05.12.01, 05.13.04, and 06.15.00
- iPhone 4 01.59.00
Unlock iPhone 4, 3GS over iOS 5 with UltraSn0w 1.2.4
Step-1
Launch Cydia and on your iPhone and navigate to Search tab and do search for latest UltraSn0w 1.2.4
Step-2
Install UltraSn0w, in result your iPhone on iOS 5 will get unlock
Note: To unlock iOS 5 with Ultrasn0w, first you need to jailbreak iOS 5 over iPhone 4 and iPhone 3GS, which you can do with latest Redsn0w tool.