This is all due to the 4.45 Firmware released yesterday that caused some systems to brick. Sony is currently looking into the issue but in order to make sure no one gets the update automatically (PS+ users mainly) PSN is currently down. I don't forsee this being a big issue nor do I see it as staying down all day, when it was up with no issues this morning. Both of my PS3's had no issues with 4.45 but apparently something with the Trophy support/notifications caused a lot of issues that you can't even restore/reformat it.
I don't think we have been hacked. I think with the reports of the 4.45 firmware bricking systems they are taking PSN down cause of the trophy features that firmware had. I bet when it comes back up a 4.46 or 4.47 firmware will accompany it. While PSN is not working the saints row download i started yesterday is still downloading as normal. So not all system are down at this time.