In the latest round of iOS jailbreaking news, it seems like Greenpois0n untethered jailbreak for iOS 4.2.1 shall be released very soon in the near future. Renowned iPhone hacker Pod2g has made the confirmation via twitter as well.

Previously, we have reported that the next version of Greenpois0n shall be untethered upon release, the good news now is that according to this Wiki, Greenpois0n untethered jailbreak tool for iOS 4.2.1 shall be supporting all of the following devices: iPhone 3GS, iPhone 4, iPod touch 2G, 3G, 4G and the iPad.
It looks like the reason due to which Greenpois0n RC5 will be released very soon is the fact that Apple has patched the loophole that hackers have been previously using up till the recent iOS 4.3 beta, meaning obviously that there is no point in waiting for a public release of iOS 4.3 and it is best that Greenpois0n is released as it is. Obviously, we know the hackers will definitely make a fresh attempt at jailbreaking iOS 4.3 soon enough.
Here’s what Pod2g has to say:
The good point is that because of this (and the fact that Apple fixed the kernel exploit in 4.3), we’re all working back on releasing gp.
So what this piece of news means is that we shall be seeing a brand new untethered jailbreak tool for iOS 4.2.1 very soon that will support all of the above mentioned Apple iOS devices. Let us see when Greenpois0n RC5 is finally released.
We shall definitely report once any updates come in.