Chronic-Dev Team has released Absinthe 2.0 for iOS 5.1.1 untethered jailbreak and the list of devices which are compatible with iOS 5.1.1 untethered jailbreak are as follows-
iPod touch 3G
iPod touch 4G
Apple TV 2G
If you want to know how to iOS 5.1.1 untether jailbreak using Absinthe 2.0 then here is the guide.
1. First take a back up of your iOS device.
2. Download Absinthe 2.0 from here and run Absinthe 2.0.
3. Connect your device to your computer running Absinthe via USB.
4. Click on Jailbreak and wait for the process to complete.It will take few minutes.
5. When the process is complete you will be able to see Cydia icon on your Home Screen.
6. Your iOS 5.1.1 device is now jailbroken untethered.