Today, a new rumor has it that the "Rebug" custom firmware for the PS3 caused Sony to desperately take down their own network, on one of the more popular weekends for gaming of the whole year.
The Rebug CFW is a mod to a proxy server, allowing users to simulate turning their PS3 into debug units used by Sony developers.
Using those mods, hackers can enter any credit card number they want and download games and other content for free from the PSN. Sony does not check the authenticity of the cards because it is assumed their own developers are not stealing content.
For now, the rumor remains just that, but Sony has sure gotten a lot of press for remaining pretty mum on why their network still remains down after 5 days.