PlayStation Network is officially undergoing scheduled maintenance and Sony is now implementing a "series of back-end improvements" to the network.
As such, certain features like the "What's New" feed, "Live Items," or your "Library" on PS4 are inaccessible. As is the Share feature. For all PlayStation gamers, PlayStation Store, PlayStation Home, and Account Management will not be available during the maintenance window — regardless of what platform you're on.
Maintenance is expected to take around four hours, and is scheduled to conclude at 1:00pm Pacific (4:00pm Eastern) time. This is Sony, though, so be prepared for some delays.
The good news is, you should still be able to play games online and access partner apps like Netflix during the maintenance as long as you have had an active account with PSN as of the start of it. This is different than the usual log in restriction that requires you have been signed in prior to a specific date.