Today, greenpois0n have already released two versions of Absinthe. One for Windows and one for Mac. The Linux version will be available for download soon.
Before you start, you need to make sure that your iPhone 4S is running 5.0 or 5.0.1 firmware. For iPad 2, make sure it is 5.0.1. This is very important in order to make it work.
After you downloaded the file above, take a look at the video walkthrough below.