Jailbreak iPhone 4, 3GS, 3G on iOS 4 / 4.0.1 and iPad on iOS 3.2.1 with JailbreakMe 2.0 Userland Jailbreak
You can now Jailbreak iPhone 4, 3GS, 3G on iOS 4 / 4.0.1 and iPad on iOS 3.2.1 with JailbreakMe 2.0 Userland Jailbreak. Comex has released his jailbreak for all iOS 4 devices including the iPhone 4.
The userland jailbreak for iPhone 4, iPhone 3GS, 3G on iOS 4 / 4.0.1, iPod touch on iOS 4, and iPad on iOS 3.2.1 is now available. It is a browser based jailbreak, all you have to do is to browse to http://jailbreakme.com from your device (iPhone, iPod Touch or iPad) to jailbreak it.
Once you have jailbroken your iPhone on iOS 4 you will be able to unlock it using UltraSn0w.
Congratulations to comex and the iPhone Dev-Team for making this happen.