The iPhone 3G has been unlocked by a X-SIM and this is confirmed by the team of GSMVN.
The GSMVN team were also responsible for the hardware unlocked iPhone for 1.1.2. They helped to discover the software unlock through GSMVN's dump methods.
Below are pictures of the process. The procedure was performed on a pre-activated phone. More information will be released once it becomes available.
(Click to enlarge)