Earlier today, MuscleNerd confirmed that he has got a “backup” method of making jailbreak untethered on iOS 4.2.1. This new method utilizes iOS 4.2b3 (Beta 3) SHSH blobs which Cydia only recently started saving for all iOS devices.
iOS 4.2.1 was released yesterday for iPhone 4, 3GS, 3G, iPod touch 4G, 3G, 2G and iPad. Even though iOS 4.2.1 jailbreak is possible via Redsn0w 0.9.6b2, but Cydia is still broken which makes the jailbreak pointless for many. It also contains new baseband for all iOS devices which currently makes it impossible to unlock using existing version of Ultrasn0w. So if you upgraded to iOS 4.2.1 and now want to downgrade back to iOS 4.1 / 4.0.2 / 4.0.1, follow the instructions posted below to downgrade iOS 4.2 on iPhone 4, 3GS, 3G, iPod touch and iPad to iOS 4.1 / 4.0.x.
