MuscleNerd from the iPhone Dev Team just tweeted that he got an untethered iOS 4.2.1 jailbreak working (video coming soon) that uses iOS 4.2b3 hashes that were kept on Cydia.

This latest method is a ‘backup plan’ as @comex is hard at work on an extensible untethered jailbreak. This new method does not exploit any new holes, so it will be safe for iOS 4.3 and will work on all devices. MuscleNerd tested this on an iPod Touch 4G. We’ll update this post with the video as it goes live.

Update 1: Video below!

ipt4g 4.2.1 untethered JB w/4.2b3 kernel: http://is.gd/inE4e … Wastes no exploits, but upcoming @comex JB maybe better

Great news from the hardworking folks from the iPhone Dev Team and more.

[MuscleNerd via twitter]