Some good news for those of you who accidentally upgraded their iPhone to OS 3.1.3 with baseband 05.12.01. According to MuscleNerd, there will be an iPhone unlock for baseband 05.12.01 when iPhone OS 4 comes out later this June.
MuscleNerd revealed this information when someone asked him about it on Twitter.
In his reply, MuscleNerd confirmed there will be an unlock for the iPhone 3GS but he also gave us a piece of advice that is too often disregarded.
It is indeed not widely understood enough that one should not update his iPhone right away when Apple pushes a new OS update. If you want to be able to jailbreak or unlock future iPhone OSs, then keep in mind not to update right away. Wait for a while until the Dev Team gives us a go or instructions to update safely while preserving the baseband.