Untethered iOS 4.2.1 jailbreak for iPhone, iPod Touch and iPad 4.2.1 will be coming by Christmas. Comex said it already and MuscleNerd also showed off untethered jailbreak 4.2.1 iOS on video few days back. Now a tweet from MuscleNerd further confirms it, here’s it:

scotty6kids78: @MuscleNerd are we any closer to the unteathered #jailbreak for the new #ios4.2 on #iphone4 ?

MuscleNerd: @scotty6kids78 it’ll be here by Xmas (not because we’re sitting waiting for Xmas, but because it’s achievable deadline)

So it seems that you’ll have updated jailbreak tools to support untethered 4.2.1 jailbreak. There have already been news for updated Greenpois0n 4.2.1 jailbreak. Redsn0w 0.9.6 Beta 5 will almost certainly get an update as well. Let’s see what other tools get updates once Comex gets the stuff working.