The iPhone Dev-Team is demonstrating an preliminary jailbreak that works on the iPhone 4S and iPad 2.
VERY preliminary 4S JB: http://twitpic.com/76vcp4 http://twitpic.com/76vct2 (Huge missing pieces prevent public release. LOTS of work left)
Here’s a short video of current JB working on iPad2: http://youtu.be/oJVGl1eRW2A (Just like iPhone4S, lots of hurdles remain, no ETAs)
According to MuscleNerd, this is a userland exploit that occurs after iBoot is out of the picture.