Heads up, developers: The iPhone Dev Team announced this weekend that Redsn0w 0.9.6b3 is now available. The update supports iOS 4.2.1 and will allow developers to bypass Cydia, which was broken in 4.2.1.
If you want your jailbreak apps ready for the official iOS 4.2.1 release, this is your ticket to do just that. More detailed instructions over at Redmond Pie. [Redmond Pie - Thanks, Anum]