Well it has been unlocked. The use a SIM adapter to simulate a fake IMSI test card. Instead of the AT&T IMSI like in the universals. What does this mean? Through the SIM adapter the network of the card is spoofed, making the iPhone believe that the SIM card is acually an activated card from an iPhone carrier. This unlock method has been used in the past using Turbo Sims, Hyper Cards, and Stealth sims. It isn't a true software unlock which we expect to see from the devs soon.
[gizmodo via techguru]