As everyone knows, the $600 Apple iPhone is designed to run exclusively on AT&T's cellular network, as well as the occasional Wi-Fi hotspot. Hackers decided that they didn't want to be forced into buying a 2 year contract from AT&T, and worked day and night to get the iPhone to run on alternative networks. Finally, we are seeing some progress. Croatians, using a particular SIM card (SuperSIM - V1, U types), a SIM read/writer, a Silvercard, and a particular software suite, succeeded in making the iPhone run on T-Mobile's European network. The hacking software works on both Mac OS X and Windows computers. The only thing lost with the hack is YouTube functionality However, considering the limited library available on the iPhone's version of YouTube, The Inquirer does not consider it that great a loss.
Source: The Inquirer