Sony has confirmed that PlayStation Network will undergo 11 hours of maintenance from tomorrow, November 7 from 14:00pm until Friday 8th November 01:00 GMT.
"If you’ve signed onto PSN over the past few days, you’ll still be able to play online and access apps during this period, but you may receive a maintenance notification when attempting to access the PlayStation Store, PlayStation Home, and Account Management as these services will be unavailable. Be sure to sign in now if you wish to access the Network during this maintenance window."
This maintenance comes ahead of the PS4 release in a couple of weeks time. Perhaps Sony is preparing its network for the inevitable rush.
You can pre-order PS4 below.