iPhone Dev Team Done it again. Only within few hourafter iOS 4.0 release they release Unlock for all iPhone on all baseband including 05.13.04 (on iOS 4) and 05.12.08 (on 3.1.3).

Musclenerd and iPhone Dev team just released ultrasn0w 0.9.3 in the wild. Latest version of ultrasn0w adds support for iPhone 3G and 3GS running baseband 04.26.08, 05.11.07, 05.12.01 and the latest 5.13.04 from iOS 4. A big thanks to Sheriff Hashim for once again discovering an all new crash to made this release possible. Newer version of ultrasn0w is available on Cydia repo, “repo666.ultrasn0w.com” where ultrasn0w is spelled with a zero, not the letter “o”.

Note: The iPhone Dev-Team has not yet released the jailbreak utilities for iOS 4. So those who want to update should wait a little bit. Those on 3.1.3 with the 05.12.01 baseband can install UltraSn0w right now to obtain an unlock.
Yet for using unlcok you first need JailBroken iPhone with Cydia, follow this guide, then just unlock with UltraSn0w.
Jailbreak iOS 4.0 with Redsn0w

You could always get support from UnlockAlliPhone.com about any Unlock & JailBreak issue of any model of iPhone including iPhone 2G,3G & 3GS and also upcoming iPhone 4. They provide Premium Members Support for life time. Means just pay one time a small fee and you will receive support(real human support – avg response time 2 hour) for all present & future version of iPhone.