According to
Escapist, their authentication servers went down early today and have been offline for over 10 hours. No one who bought their games can actually play them, and the rep says he's trying to get more info and hoping everything will be back online by tomorrow.
Again....That didn't take long, now did it kids?
EDIT
RPS has picked up on this as well.
AlabasterSlim Says:
March 8th 2010 @ 9:52 am EST
Looks like it was caused a DOS attack.
RPS Article