DON'T UPGRADE TO 3.1.3 - YOU WILL LOCK YOURSELF OUT IF YOU DO!
======== SIMPLE UNLOCK INSTRUCTIONS =========
blackweather - download the Windows version (The big windows logo at the bottom)
plug iPhone into computer
run tool
Install "sn0w" in the newly installed Blackra1n app on your phone, or goto Cydia (also installed) and download Yellowsn0w
Restart phone