I just did the update to FW 3.1.3 and used redsn0w to jailbreak. It worked fine...no problem. I did not have the unlock. If you are interested in the unlock (like blacksn0w), stay away from this. This is JB only. Here's what I did, FYI. BTW, I used a Mac. 1. Backed up iPhone 3G to iTunes. 2. Copied the iPhone 3.1.2 firmware from Library/iTunes to desktop 3. Downloaded iPhone firmware 3.1.3 with iTunes 4. Restored iPhone 3G with iTunes. 5. Did not set up as new phone; restored using last backup 6. Downloaded and installed redsn0w 0.9.2. Closed iTunes. 7. Ran redSn0w, pointed it to FW 3.1.2 on the desktop, installed Cydia only. 8. That's it!