iOS 4.2.1 Untethered Jailbreak For iPhone 4, iPad And iPod Touch 4G Released

As expected, iPhone Dev team has just released a new version of Redsn0w (Redsn0w 0.9.7b1) that implements the “backup plan” for iOS 4.2.1 untethered jailbreak.

Redsn0w 0.9.7b1 can be used to (untethered) jailbreak iPhone 4, iPad and iPod touch 4G on iOS 4.2.1. Please note that Redsn0w 0.9.7b1 is meant only for beta testers and not for the general public as there are still some known issues that need to be addressed.

Please go through the following points before trying the new version of Redsn0w:

This is a beta tester program. It’s not a general release! Things can go very wrong, so please don’t even consider testing if you have pictures or other media on your device that you haven’t backed up!
For the same reason, please don’t participate if you rely on the ultrasn0w carrier unlock. Wait for the final version!
Until we fix some sandbox issues with bluetooth, the bluetooth functionality is disabled.
This very first beta1 is limited to iPhone4, iPad, and iPod touch 4G.
Cydia must have your 4.2b3 SHSH blobs saved on file. (As we approach a general release, we’ll provide a way to let you use locally saved hashes too).
You must already have the usbmuxd software installed and running on your Mac (this requirement will eventually go away too). The correct invocation of the relay is just as that page says: “./tcprelay.py -t 22:2222”. If the relay isn’t installed or running correctly by the time the redsn0w ramdisk has started, you’ll need to restore to stock FW again to try it again. Please test it beforehand to save yourself some time!
It is also important to note that jailbreaking your iDevice may void its warranty so please proceed with caution and at your own risk. It is always a good idea to take a backup of your iDevice, refer to this post for more details.

Please note that these are some of the known bugs:

Task switcher causes Springboard crash (temporary workaround is to use SBSettings process list)
Bluetooth currently disabled due to sandbox problem
You can checkout if Cydia has saved iOS 4.2 beta 3 SHSH blobs, launch Cydia and wait for it load the main page. You should see SHSH: 4.2b3 on the top of the page.

If you plan to give it a shot then download Redsn0w 0.9.7b1 for Mac using this link. Please don’t forget to let us know how it goes in the comments and also provide your feedback on Dev Team’s blog, which will help them to iron out the issues before the public release.