Via their forums, Sony revealed that they will be taking PSN down for a few hours this Monday, January 27th, for some regularly scheduled maintenance. PSN will be down from 12:30 PM to 6:30 PM (Eastern time). Thankfully, if you have logged into PSN since January 20th, you will still be able to play online and access apps such as Netflix, Hulu, Vudu, etc. The Playstation Store, Playstation Home, and account managements sections of the XMB will be completely inaccessible.
If you’ve signed in to PlayStation Network any time since January 20th you will be able to play games online and access partner apps such as Netflix during this maintenance period. The PlayStation Store, PlayStation Home and Account Management will not be available during this time, and users may receive a maintenance notification when attempting to access these services.
Unfortunately, Sony did not detail what exactly they would be working on improving.