Wow Sony. This is a big whoops!
Remain in the dark no longer! Your questions are answered.

A glitch in the Playstation 3 systems caused a serious uproar yesterday when users found that they could not connect to the Playstation Network or for some, even play their PS3 at all. The glitch also raped certain users of their player data and game achievements which devastated players with all their hard earned trophies. Sony has not released any information on the number of data loss casualties, as they are kicking themselves in the butt right now for having their market just finally pick up.

Sony has confirmed that the error was caused by a Y2K-like glitch in which the older models viewed 2010 as a leap year. Owners of the newer Slim models appear to be unaffected by this catastrophe while older system consumers remain scared and torn from the incident.

Thanks to Joystiq, be not confused any longer! Your questions are answered:

Q. Is it safe to turn on my PS3 now?
A. Right now, it appears the answer is “yes.” The PlayStation Network is online and fully functional for owners of the PS3 Phat system, and games appear to be running problem-free. Sony has yet to issue an official “you can use your PS3″ statement, however.

Q. Do I have to download a firmware update?
A. Nope. The problem should just fix itself automatically, whether you’re online or not.

Q. My Trophy data for [insert game here] is gone! (I know, I know — that’s not a question, but still!)
A. If you lost any Trophy data over the past 24 hours, there may be a way to salvage it. Launch the game for which you’re trying to restore Trophies and it should automatically recreate a Trophy data set on your PS3’s memory, which you can then sync with the PSN server (just by opening up your Trophy list in the XMB). Our Heavy Rain Trophies had vanished, but this trick brought them back from the ether.

Q. The time and date on my PS3 are wrong. How do I fix this?
A.Under Settings in the XMB, then under the Time/Date settings, you should be able to set your console to automatically sync the time and date via the internet.

*A moment of silence for all the PS3 users that were robbed of their hard earned gaming careers, I hope you are able to restore your achievements & may the force be with you..*

Source: [Playstation.Blog] [Joystiq]