The Sony network went down some time last night, and remains down today. Most news sites are saying that it could be at least another day before things are up and running again. It is apparently not due to hacking, but some other unspecified cause.
No COD: Black Ops for me tonight I guess.
On a side note, today is supposed to be the day stated in the Terminator movies that the machines first take over. Could this be the beginning of the end? Lets hope not, I still have a prestige level to finish!
UPDATE APRIL 26: Found THIS blog post at the Playstation site just now. Looks like there is no end in sight! At least they have actually come out with a bit of an explanation this time.