Sony has announced that scheduled maintenance for PlayStation Network will take place on Thursday, January 15th, from 9:00am to 1:00pm Pacific Time (12:00pm to 4:00pm Eastern).
During this "approximate" four hour window, Sony will deploy "a series of back-end improvements to the network." Unfortunately, they didn't go into any more specifics.
Although PSN has been stable of late, the online service has been suspect in the past. In December, Sony fell victim to a number of DDoS attacks that brought down PSN for a number of days. Shortly after the DDoS ended, PSN went down again due to "heavy network traffic." Even today, the official PSN status still warns of heavy traffic.
So while it's unclear what Sony's back-end improvements are exactly, we're hopeful it will address the problems experienced in the past and prevent them from happening again.
Sony notes that if you've signed in to the network any time prior to October 8th, you should still be able to play games online and access partner apps like Netflix during the maintenance. However, PS4 users will be unable to access the "What's New" feed, "Live Items," or their "Library." Share features will also be affected by the maintenance. The PlayStation Store, PlayStation Home, and Account Management will not be available either.
Having said all of that, these maintenance periods can be wonky things that often interrupt your gameplay sessions. So be prepared for some unexpected disconnects. And also be expected for the maintenance to be extended, because that's just what Sony tends to do.