How to Unlock on iOS 4 / 4.0.1 (Any Baseband)

iOS 4.0.1 has just been released by Apple for iPhone 4, iPhone 3GS and iPhone 3G to fix the reception issues which has been problematic for most iPhone 4 users since its launch last month. iPhone 3GS and iPhone 3G users who currently rely on an unlock MUST STAY from iOS 4.0.1 until any further notice. Updating to iOS 4.1 might result in update of baseband, which will potentially lock your phone. You wont be able to unlock it until a new exploit is found again.

How to Unlock iPhone 3GS and 3G on iOS 4 with Ultrasn0w

UPDATE 1: After thorough testing, it turned out that baseband and modem firmware for all iPhones hasn’t been updated in iOS 4.0.1 since iOS 4. What this basically means is that you can still unlock your iPhone on any baseband using ultrasn0w, guide for which can be found here. But since currently there is no jailbreak tool available for iPhone 4 and iPhone 3GS (new bootrom), and the current jailbreak tools for iPhone 3GS (old bootrom) are not compatible with iOS 4.0.1 yet, so the only device which can be currently be jailbroken and unlocked on iOS 4.0.1 is iPhone 3G