? when you upgrade your iOS, it doesn't wipe anything... (but maybe I'm reading this wrong or something)... anyway Absinthe WILL NOT install 5.1.1, you'll need itunes-
but be sure to back up first on itunes and then wipe (
see the instructions on installing absinthe**) that way once you JB, you can just restore and get all your stuff back (and keep the jailbreak)
I don't think it's necessary to wipe, but the process goes by much faster if you just wipe
**
Absinthe 2.0