Although the Chronic Dev Team announced some time ago that they are working on an untethered jailbreak solution for iOS 4.2.1, so far the only thing I have seen from them has been constant arguments with the Dev Team. Appearances are often deceiving and although the 2 teams were arguing, the Chronic Dev Team was preparing a release of the new jailbreak solution for the first day of 2011, but unfortunately they encountered problems in the implementation of the exploit and had to postpone it . p0sixninja announced on his Twitter account that greenpois0n rc 5 will be available soon without specifying any clear date.
Before you get too excited, I inform you that the new jailbreak solution will not be untethered for all terminals, but only for those with old bootrom. If you have an iPhone 3GS(new bootrom)/4 or iPod Touch 2G(new bootrom)/3G/4G or iPad then you will not be able to do untethered jailbreak. Basically, this new version of greenpois0n will not bring anything important compared to redsn0w, but probably just a simpler method to jailbreak.
