If you want an unlocked 3G iPhone, you have a couple options. If you haven't upgraded to 2.2, you can try your luck with one of those SIM piggyback wafers; otherwise, you can try importing from a country like Hong Kong, which sells unlocked iPhones officially.
There's a third option, though: take a trip to Hanoi, for 1.2 million dong (snicker! Also: about $80) you can have your iPhone 3G physically unlocked by an industrious Vietnamese mobile phone hacker.
First, a technician opened up the phone and stripped it to the motherboard. In his skillful hands, the device seemed much easier to dismantle than I expected.
The technician then extracted the baseband chip, the component that controls the connection between the phone and the mobile network, from the motherboard. (This is a painstaking task as the chip is strongly glued to the phone's motherboard. A mistake during this process could brick the phone completely.)
Once the chip was extracted, it was Tuan Anh's turn. He used a chip reader to read information into a file. He then used a Hex editor to remove the locking data from the file, and after that, the chip got reprogrammed with the newly altered file. Now it was no longer programmed to work with only a specific provider.
The chip then got reassembled into the motherboard, another painstaking process.
As a last step, the technician put the phone back together, and it looked like nothing had been done to it.