Well, here's some good news! MuscleNerd has just announced on his twitter account that he's going to release a new ultrasn0w today along with the untethered jailbreak on iOS 4.3.1.
BTW ultrasn0w needs an update for 4.3.1, so unlockers should wait until that gets pushed out (hopefully also today)Stay tuned for today! NO! It's not for iPhone 4!