The PlayStation Network is currently down due to maintenance from 5:00 PM PT - 6:00 PM PT. Sony hasn't warned users about this scheduled maintenance; probably because it'll only last for an hour or so.
From Sony support:
"During this time you may:
* Not be able to access the PlayStation®Store
* Have difficulty signing in to the PlayStation®Network
* Not be able to play online games
* See a maintenance page when attempting to access the PlayStation®Network
Note: When you log into the PlayStation Network, a message may appear which states, "the PlayStation Network has been suspended". This does not mean that your account has been suspended; it simply means the PlayStation Network has been taken offline. Please wait until the maintenance window has passed before attempting to connect to the PlayStation Network again. We apologize for any inconvenience this may cause."
So even though Sony didn't give gamers a heads up that the service would go down, it seems that they have this under control.
Keep Calm and Carry On.