Engadget has posted the whole of a successful iPhone unlock on video, here.
According to Daily Tech, "the iPhoneSimfree software is now available for purchase. Currently, four online retailers in the world hold licenses for the unlocking software: Wireless Imports in the US, iPhoneWorldwideUnlock in Australia, 1digitalphone in Germany, and iPhone4arab in Saudi Arabia. Current prices for a single unlocking process range from $50 to $100."
Update: Engadget has now confirmed that iUnlock, the first free, open source iPhone SIM unlock app, works. It also has the background story.