An untethered iOS 4.2.1 jailbreak for iOS 4.2.1 on iPhone 4, iPhone 3GS, iPod touch 3G, iPod Touch 4G and iPad is now available in the form of greenpois0n RC5! This is excellent news for all those who were waiting for an untethered jailbreak for their iOS device to get rid of the annoying re-jailbreaking required on every restart, especially after installing Cydia apps.No longer do you have to rely on a tethered redsn0w jailbreak for iOS 4.2.1 though! Thanks to greenpois0n RC5 by the Chronic Dev Team.
A word of caution, though, greenpois0n is available for only Mac OS X for now. If you’re aware of how to work with greenpois0n, go ahead, download it from the link below and enjoy! Else you can wait for a while we compile easy and helpful guides for your iOS device and publish them!
Download greenpois0n RC5 for iOS 4.2.1 Jailbreak
Download greenpois0n RC5_2 for iOS 4.2.1 Jailbreak (fixed Stuck At Greenpois0n Initialized Screen Issue )
UPDATE: Our complete step-by-step guide is now available: How to use Greenpois0n RC5 To Untether Your Device On iOS 4.2.1.