i made a small script which is able to root ICS/JB phones. It uses a remount timing issue in Androids "adb restore" service.
So normally it should work on nearly all ICS/JB devices, for some it won't but the idea may work in a slightly modded version
There is a special case for Xperia T and Xperia S,P etc. phones, this phones run ICS but don't have android's native restore with adb, Sony has added a own custom "Backup&Restore" app, the script handles this cases too, just choose the correct option!
Have fun with it and if you like you can donate to me
1.) Download attached file.
2.) Extract it using 7zip
3.) Double click the RunMe.bat and follow instructions!
1.) It DOES delete the old backups which are made by Sony's "Backup&Restore" program into INTERNAL MEMORY, SDCard Backups are untouched! Sorry for that! That is the "only" bad side
2.) This does not wipe any other data, dont worry!
Sony Xperia : S, T, P , Acro S
Google: Nexus 7 (thanks Paul O'Brien for test