Gevey has released the Ultra 5.1 to unlock the GSM iPhone 4 on iOS 5.1.

The new GEVEY Ultra unlocks your GSM iPhone 4 running iOS 5.1 and earlier and now supports modem firmware versions 1.59, 2.10, 3.10.1, 4.10.1, 4.11.08, and 4.12.01. Currently, a tethered Jailbreak is available for iOS 5.1 for iPhone 4, and you will also need to install the latest Furious Mod file for proper operation.

Additional software needed and tested to unlock your iPhone 4 with the new GEVEY Ultra are Redsn0w 0.910b1 and Absinthe v0.4. Note that we cannot offer phone support for installation, configuration, or troubleshooting of the iPhone Jailbreak process.

You can purchase the GEVEY Ultra 5.1 for $49.99 from the link below...