The iPhone Dev Team has released new information regarding iOS 4.2.1 jailbreak and unlock situation, which is as follows.
Apart from iOS 4.2.1 for iPhone, iPad and iPod touch, also released today is iOS 4.2 for Apple TV 2G which brings video AirPlay feature that will allow you to stream pictures, videos and music right from your iPhone, iPad or iPod touch to TVs connected to the second-gen Apple TV.
Its official now! Apple has just issued a press release, confirming that the much awaited iOS 4.2.x software update will be be publicly available today for download via iTunes 10.1. Full press release is as follows
The recently released Redsn0w 0.9.6b3 can jailbreak all iOS based devices including the new A4 devices like iPhone 4, iPad and iPod touch 4G. Since Cydia included in this version of Redsn0w is not compatible with iOS 4.2.1, you can use the following steps to install a patched version of Cydia.
The iPhone Dev Team has just released Redsn0w 0.9.6b3 which brings support for iOS 4.2.1 GM firmware file. The highlight feature of this release is SSH and SSL support which will now allow you to install bundles and packages independent of Cydia, which is currently broken on 4.2.1.
I have just jailbroken my iPad on iOS 4.2.1 using PwnageTool bundles released by Johnny Franks. These bundles can be used to jailbreak the newly released iOS 4.2.1 GM on both iPad and iPod touch 4 with working Cydia !
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.
After releasing a revised version of iOS 4.2 GM for iPad to developers last week, Apple has now seeded iOS 4.2.1 GM for iPhones, iPad and iPod touches. This build is meant for developers only. Only members enrolled in the iPhone Developer Standard or Enterprise Program can access these bits of by signing into Apple Developer Connection.
The official Twitter blog has just announced full iOS 4.2 compatibility for iPad and iPhone clients, and official push notifications support for Direct Messages (DMs) and Mentions for Twitter for iPhone client.
New version of iREB for all iOS 4.1 devices is now available for download. You can use it to bypass 1604, 1603, 1602, 1601, 1600 error in iTunes during custom iOS 4.1 firmware restore which has been created using either Sn0wbreeze or PwnageTool.

