These are only things I remember, so it may not all be true.
Apparently, Sony is being attacked by hackers, which has caused Sony to close PSN for maintenance. It should be back to normal today or tomorrow. If there's still trouble, it may take longer. If you only have PS3, or use it more than other systems, this is going to be a bad weekend.
When PSN is back online, the Admin(s) and/or Moderators can lock this thread if necessary.