what cerbrus2 was partially correct
a group of hackers, following a turk called Anonymous, hacked the PS3 in the same fashion that was used to illegally install "backed-up" game copies on the PSP (pandora).
this person, Anonymous, was found and dealt with about a month ago. The result was won by sony without a lengthy legal battle. the sites were brought down, and the code was given to sony. sony used this code to quickly issue a patch for the PS3 systems
However, another group, who felt bad for Anonymous's struggle with sony (and threw their rattles out of the cot), launched their own attack on the servers, NOT external systems.
the new attack has brought to light new flaws in the server-side architecture. so, they have actually done sony a favour.
to my knowledge, sony will be releasing a completely new firmware for all PS3 systems. it will appear as a new update, but will really be a fresh OS install. only very few gamesaves will be affected.