Chronic Dev team has released Rocky Racoon 5.1.1 Untether jailbreak on Cydia which enables users to convert tethered jailbreak into untethered jailbreak after releasing Absinthe 2.0 for iOS 5.1.1 untethered jailbreak.
According to Chronic-Dev Team -
Rocky Racoon is the underlying untethered jailbreak that will be installed by popular jailbreak tools such as redsn0w and absinthe… if you are using 5.1.1 and you can reboot your device and have it still jailbroken, you have Rocky Racoon.
If your device relies on Rocky Racoon on untethering, which includes any iPad 2, iPad 3 or iPhone 4S running 5.1.1., uninstalling this package will unjailbreak your device.
Convert iOS 5.1.1 Tethered Jailbreak to Untethered Jailbreak Using Rocky Racoon 5.1.1 Untether
Launch Cydia >> Install Rocky Racoon 5.1.1 Untether by searching >> Reboot your device now.
If your iOS device reboots without performing a tethered boot then it means that your jailbroken device is now converted to untethered jailbreak.