If you've updated your iPhone 3GS to iOS 5 or 5.0.1 and lost your unlock we can help you get it back. The actual jailbreak will be tethered but you'll still be able to unlock and continue using your device in the mean time until an untethered jailbreak solution is released. iPhone 4 and iPhone 4S users should steer clear of this as it will not work.
You'll follow the same steps are you would to jailbreak via Redsn0w except for one difference. Instead of just checking Install Cydia you'll need to check off Install iPad baseband. RedSn0w will warn you that this can not be undone. Agree and continue the jailbreak process.
After jailbreaking you'll need to perform one tethered boot before unlocking. Simply launch RedSn0w again and click Extras. Check the box for Just boot tethered right now. You'll be walked through DFU mode and your phone should reboot.
After your phone reboots you'll need to perform the following steps to unlock it:
A few users have seen issues where their phone will not obtain service after using ultrasn0w on iOS 5 or iOS 5.0.1. If you have this issue, launch RedSn0w once more and choose jailbreak again. Instead of going through the whole process this time, you only want to check Deactivate. Do one more tethered boot and you should be good to go!
If you need more help, visit our TiPb jailbreak & unlock forums for answers to many common questions and to ask your own!
Update: Some users are pointing out that using RedSn0w 0.9.9b8 is breaking GPS functionality again but using RedSn0w 0.9