According to Joystiq the reason Sony shut down PSN was because of a custom firmware named rebug that allowed people to get PSN games for free. For the people who don't understand why Sony sued Mr. Hotz and the other PS3 hackers this is why. For every person who might hack a console to come up with some homebrew games or put in features that manufactures didn't put in there are 100,000 for that 1 who just wants to pirate games or hack games and ruin the multiplayer experience for everybody.