[Update] Aug/25th/2008: read here [1], everything you gotta know about Proxy SIM solutions.
The Bladox Team has released an application for their Turbo SIM (see here [2] how proxy SIMs work) that is obviously able to bypass the SIM lock of 3G iPhones – means unlocking it. The application is still beta and might not work on the entire planet, but it obviously does in the U.K. The name of the app is zerog-0.95.tar.gz, but for legal reasons we will not directly link it.
See this video:
It takes ages until it is logged it, but anyway it documents the current status quite well…