And you can finally install Cydia, have 3G Unrestrictor 5 and CDevReporter and many other goodies await for you to grab once your iPhone 4s and iPad 2 jailbroken with Absinthe. Anyaway let's do it to jailbreak A5 untethered with Absinthe.
Step 1) Download and extract Absinthe 0.1.2-2 latest version from the .zip and start Absinthe. (Currently for Windows).
Step 2) Now let's connect your A5 devices (iPad 2 and iPhone 4s) to your PC and then hit Jailbreak button on Absinthe window.
Step 3) Keep pressing the Jailbreak, Absinthe will do its task to untethered jb your device, and this will take sometimes and you will be taken to number of steps so just wait.
Step 4) Then a complete message will appear, means the injection of Absinthe to your device is complete and then your A5 device will automatically reboot.
Step 5)After it's rebooted you will find out that your A5 device is untethered jailbreak already!
Update 1: If you find bugs after jailbroken, then visit this page to fix camera empty and error establishing a database connection and fix Absinthe white screen.
Update 2: Absinthe for Windows will be released soon.
Update 3: Jailbreak for Windows is available now. Visit this post to jailbreak iPhone 4s, iPad 2 untethered for Windows using CLI Tool.