As if speculations of why Sony’s online service PlayStation Network hadn’t reached pointless levels, here’s another one for you. According to PSX-Scene.com moderator chesh420, the outage occurred due to Rebug, a CFW (or custom firmware) that basically turns your retail PS3 to a dev console, giving you virtually the same access to PSN as any developer today has.
Apparently, by manipulating Rebug a fair amount, you could enter a fake credit card number and since you’re now on Sony’s private PSN for developers, it wouldn’t check if that info was correct or not, leaving the entire PSN exposed for downloading content by the masses.
While that is a big issue for Sony, who’s hopefully rebuilding PSN to be more secure in the future, let your fears be put to rest of the fact that any sensible information you might have entered through your PSN account, such as credit card numbers, are not at risk at this time. (update: maybe not)