Currently it updates Backtrack, metasploit, exploit-db, SET, Warvox, Aircrack-ng, Gikismet, Nessus plugins, W3AF and Nikto. It saves a lot of time compared to doing it 1 by 1. The script can also update itself and there will be more tools implemented in the future.
Installation is quite simple:
gcc -o backtrack5_update backtrack5_update.c
To run it just do ./backtrack5_update