The iPhone Dev team has announced that a free carrier unlock for iPhone 3G and iPhone 3GS models is now available for download. The new unlock exploits the same AT+XAPP vulnerability that was used in the earlier unlock. Apparently, the first iPad firmware – version 3.2.2 with baseband version 06.15.00 is still vulnerable to the older exploit.
So the latest unlock basically needs your iPhone to download the IPSW of this iPad firmware (which incidentally is quite compatible) and then carry out the rest of the unlocking instructions.
If you are a Mac user, you can go ahead and check out for the instructions to carry out the PwnageTool unlocking process here. Windows users can instead choose to check out instructions for RedSn0w from the same link above.