Apple is getting tougher against unlockers with each firmware update to the iPhone. Yesterday the 3.1 update was released. The iphonedev team which released pwnage tools to unlock even the 3GS is sending out a warning message.
3G+3GS unlockers must still stay far away from official 3.1. There’s no known way to revert from 3.1’s 3G+3GS baseband
This message comes from MuscleNerd who is part of the team which releases the unlocking tools . What this means that there is no way to re-virginize the 3G and 3GS phones once you upgrade to 3.1 .
2G iPhone users seem to be the least affected. But don’t worry these guys have already found a hack around which will be released soon. For updating your iPhone 3G/3GS to 3.1 you need a pre-hacked firmware file which is expected to be released soon. So stay away from the official update until this fix is out if you don’t want to turn your expensive gadget into a mere paper weight.