iOS: That was quick. The Chronic Dev Team has just released its new jailbreak too, Absinthe 2.0. and it works with the new iPad, iPhone 4S and other models running iOS 5.1.1.
Like all jailbreaks, this one requires the OS version it was meant for so if you don't have iOS 5.1.1 you should update your phone first. Once you're done, check out Absinthe's site and download Absinthe.
It'll be the same process to previous jailbreaks with GreenPoison/Absinthe. Plug your iDevice in and launch Absinthe, click "Jailbreak," and wait for Absinthe to complete the jailbreak.