It's worth noting, as Endgadget has already mentioned, that you unlock your phone entirely at your own risk; never mind the fact that a future update may brick you (although we hope not!). If the procedure seems daunting -- it involves downgrading to the 1.02 firmware to start -- blogger Pinky's Brain is working on a walkthrough that should simplify things (link via Apple 2.0). The ModMyiPhone boards also indicate that a version of the unlock, runnable on a 1.1.1 jailbroken phone, is packaged and in the repository there.
Is it worth diving into a new unlock tug-of-war with the official SDK (and, presumably, more exploits closed off with updates) in the near future? Guess that depends on how much you like having your iPhone working in the remote corners of the globe.