Method for ICS build number 6.1.B.0.544 and 6.1.B.0.559 update:
Rooting via Flashtool:
1. Download Flashtool 0.9.6.0 from Flashtool Homepage: http://androxyde.github.com/
2. Install it on your PC
3. Run the Flashtool and connect your phone (enable USB debugging first/turn on unknown sources)
4. Hit the Root button (second in row)
5. When you see “waiting for restore to finish” open your phone and run Backup&Restore app and restore RootMe.tar file.
6. Wait until Flashtool do the rest of work