updated 09:30 am EDT, Fri April 16, 2010
Awaits support from developers
The unofficial iPhone Dev Team has released the redsn0w 0.9.5 beta, believed to be the first publicly-available jailbreak for Apple's iPhone 4.0 firmware. The code relies on the same basic exploit used since iPhone 2.x, and in theory allows people to run unofficial apps. Because iPhone 4.0 itself is new however, the hack is really intended for developers intending to transition their apps to the new firmware.
A number of other limitations exist as well. redsn0w 0.9.5 operates exclusively on Macs at the moment, and can only jailbreak an iPhone 3G (not a 3GS or an iPod touch) running iPhone 4.0 beta 1. The Dev Team also cautions that users must have already activated their iPhone with iTunes and a legitimate developer UDID. Many existing jailbroken apps do not run properly, and the tool cannot be used as a step towards unlocking, since the act of upgrading to iPhone 4.0 overwrites (currently) hackable baseband. ultrasn0w and blacksn0w may be able to unlock the firmware in the future, the Dev Team suggests.