You probably know this already given the frequency of such events, however we thought we would let you know that there is PSN maintenance planned for this Thursday.
According to the post on the official PS Forums:
“PSN maintenance has been scheduled to take place on Thursday 15th December from 16.00PM until 02.00AM GMT on Friday 16th December.
Users who attempt to Sign in during the maintenance window may receive a maintenance message.
Users who are already signed into the PlayStation Network should not be affected.”
If you are signed in before maintenance takes place then you will probably still be able to play online.