Joshua Hill of the Chronic Dev Team, better known as p0sixninja, has revealed through his tweets that the team is working on their own untether for iOS 4.2.1 to include in the next version of GreenPois0n jailbreak tool rather than releasing a tethered version, the likes of Redsn0w 0.9.6.

Following is the conversation that took place on Twitter:
p0sixninja: A lot of people are saying another tethered jailbreak is pointless, I agree. Focusing on getting untethered before release
@p0sixninja I assume you are talking about Greenpois0n? Are you implementing Musclenerd's untether or do you have your own?
@tahu363 we're implementing our own
@p0sixninja I'm assuming "your own" will require 4.2b3 shsh? And thanks for your guys work!
@Capsfanchad lol no
What this conversation basically reveals is that the Chronic Dev Team will not be implementing the untether exploit from Comex and will not require iOS4.2b3 SHSH blobs like Redsn0w 0.9.7 does. Joshua has said that the team is working on “our own”” untether exploit.
There is no word as yet when the next version of GreenPois0n jailbreak tool can be expected, however we shall be sure to report when any updates come in.