Joystiq has some details about the cause of the PlayStation 3 meltdown, you can read it over here.
While early reports seemed to indicate PlayStation Network was at fault – "playstation network down" was a top Google search term on Sunday and Sony itself continues to pin the blame squarely on PSN – it became increasingly clear that the issue was unrelated to the console's internet connectivity and instead related to the console's internal clock. If this sounds suspiciously similar to the Z2K bug that suddenly bricked thousands (dozens?) of 30GB Zune players in 2008, it's because both the PS3 and Zune share an ARM CPU chip, says DF. This is presumably the same Freescale processor blamed for Z2K, a chip that happens to have a known problem dealing with leap years.