Two weeks after the release of the iPhone 4S, a member of the iPhone Dev-Team has discovered a "very preliminary" jailbreak for iOS 5 running on the iPhone 4S and the iPad 2, according to iClarified, via TechCrunch.
Dev-Team member @MuscleNerd announced the jailbreak on Twitter, posting two screenshots as proof, but advised that there are "huge missing pieces" and that it is "just a foot in the door" with no ETA for public release.
The Dev-Team previously released a tethered iOS 5 jailbreak via Redsn0w version 0.9.9b5 for the iPhone 3GS, iPhone 4 (both GSM and CDMA versions), first-generation iPad, and the third- and fourth-generation iPod Touches, but this is the first time there's been a jailbreak for the iPad 2 or the iPhone 4S. There is also a "semi-tethered" jailbreak available for iOS 5, which means your jailbroken iDevice isn't completely useless after a reboot when you're not near a computer.
@MuscleNerd also posted a super-short video of a jailbroken iPad 2 running Cydia, but it's not very explanatory or descriptive.