The iPhone 4S goes on release today but the operating system that powers it, iOS 5, has already been jailbroken.
Earlier versions of the OS were cracked as it went through various BETA stages following its release in the summer. But this time, the release is done through Redsn0w which is the computer-friendly consumer app that takes all the pain out of jailbreak for mere luddites.
Unfortunately, the jailbreak won't actually work on the 4S but will work on iPhone 4 handsets which have updated to the newer OS. iPad 2 support is also not yet forthcoming.
It's a tethered jailbreak - which means that you'll have to plug your phone into the computer every time you power it on - and therefore, it reduces freedom for the majority of users who'll not want to stray too far away from their homes. Well, unless you're rocking a 3GS, that is. On the older device, it works as an untethered break.
Still, it's good to know the iCat and iMouse game is still going strong. More details available from those nice chaps at the Dev-Team.