Beware: the new firmware update released today will update your baseband and make your phone once again not unlockable. If you rely on blacksn0w (or ultrasn0w) for an unlock on your 3G/3GS, do not upgrade your phone to 3.1.3 official. Wait for a new version of PwnageTool to be released. Please note: if you have already updated your iPhone 3G or iPhone 3GS to version 3.1.3, there is nothing that can currently be done to jailbreak or unlock your iPhone, so please do not ask. It may be weeks or months before your iPhone can be unlocked again. And, yes, it may never be unlockable again. Sorry!