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.
We'll keep you up to date with information on how this jailbreak progresses and when its available for public use. Follow us on Facebook or Twitter for updates.