Now days iPhone users are suffering to unlock their jailbroken iPhone on OS version 3.0 & 3.0.1 because http://repo666.ultrasn0w.com is not working and getting bad source error while adding this source in Cydia.
You can search this error with Google to fix this issue and to unlock the jailbroken iPhone.
Follow the steps to fix this issue:
Untrasn0w Manual Install Instruction:
2. SSH into iPhone
3. Place deb file in var/root/Media/Cydia/AutoInstall (If Cydia/AutoInstall dont exist, create them)
4. Reboot iPhone AND respring