PSN is currently down at the moment, and apparently the PS3 is having similar problems to what Zunes had about a year or two ago when it came to Leap Year. Instead of your PS3 being able to fire up, the date refers to December 31, 1999 and will not connect to PSN.
There is currently no fix for this problem, but it is advised to just stay off your PS3 until this issue is resolved because...
#1 - You will lose your trophy progress of any game that has a Trophy list
#2 - Might cause irritation, rash or skin disorder
#3 - It is unknown how far this issue goes
EDIT: Everything is now safe