There has been some news about the 4.2.1 jailbreak lately, but the unlock has been missing in action for some time. However, we got a little ray of light about ultrasn0w on Twitter from Egyptian baseband hacker Sherif Hashim, who worked on the 3.1.3 unlock. He's still keeping it on the down low - English-only speakers would have missed it - but he's indicated the unlock should be ready in about a month.
Sherif Hashim found an exploitable baseband crash that could bring an unlock for basebands 05.14.02 and 02.10.04 back in November. Very little has been heard since then, and nothing definitive as to the timing on a new ultrasn0w for iOS 4.1 and 4.2. One impatient unlocker sent Hashim a tweet in Arabic, saying he was going away for military service on January 16 and asking if the unlock would be ready by then.