The PlayStation Network will be undergoing maintenance next Monday, for over 12 hours. The maintenance window will start on September 10th at 16:00 BST, lasting until 5:00 BST on Tuesday morning, September 11th 2012. As usual, you won’t be able to play online, access the account management features or the PlayStation Store.
Also, PlayStation advise that there may be some additional downtime after the maintenance period for testing purposes.