According to Sony, they will be conducting maintenance to the Playstation Network beginning on Thursday, November 17th from 8am until 10pm PST.
"During the maintenance, you will be unable to access the following services:
- PlayStation Store on PS3 and PSP.
- PlayStation Network Account Management.
- PlayStation Network Account Registration.
During this maintenance, you can continue to collect in-game Trophies and these will be updated on your profile once PlayStation Network is back up and running.
Stay tuned to the PlayStation Twitter feed for updates and a notice when maintenance has concluded." – Patrick Seybold