Apparently, PSN has taken a sudden left turn to crapsville.  It could be PSN or it could be a firmware problem.  People are being kicked from playing certain games to their XMB (Heavy Rain, for example), the date and time are displaying as 12/31/1999 (Y2K10?), and some trophy data has also been disappearing. The error code in question is 8001050F.  If you're concerned about losing your trophy progress, don't play a game with trophies. Go and do something else until the smoke clears from this and the problems are solved. 

The only official word we have from Sony is from the PS Blog's Twitter page:

"We're aware that many of you are having problems connecting to PSN, and yes, we're looking into it. Stay tuned for updates."

We'll keep you as updated as we can here, but we're scrambling for facts right now. 

We have an ongoing discussion in the forums trying to solve this puzzle.  You can view the thread here. 

Update (8:43 PM PST): Sony just made a couple of tweets.  They are posted below.

PSN status update: We're narrowing down the issue and continue to work to restore service to all. Updates as soon as we have them.

PSN status update (part 2): Readers/followers are confirming that "slim" units (120/250 GB models) are connecting normally.

Update (3:55 PM PST): Members are now reporting that they can log back into PSN.  Still waiting from an official word from Sony, but it seems to be fixed, they may be in a testing phase right now.  Personally, I'm going to wait for an official "all clear" sign from Sony.  If you're going to try and hop on PSN, be aware that the servers are going to flooded, so if you can't log in, be patient and try again later. 

Update (7:01 PM): There you go folks.  About an hour ago, Sony waved the all clear flag.   You can return to PSN and your games.