Jailbreakers !!! Good news for those who had accidentally updated to OS 3.1.3 and lost blacksn0w/ultrasn0w unlock because of baseband update. Sherif_Hashim(twitter name) has found out an exploit on latest baseband 5.12.01, which means baseband is hackable, and we can expect a soft-unlock soon.
Sherif_Hashim informed MuscleNerd of Devteam about the exploit that he found. MuscleNerd has confirmed that it is working. Now its upto Dev team that when they are going to release the soft-unlock. According to sources they will wait for iPhone4G, because they don’t want apple to fix the exploit on their next release.
UPDATE: Good news junta: The unlock is out. Details here (works for 3GS / 3G running 3.1.3)
UPDATE: How to get iOS 4.0 on your iPhone 3G and unlock it