The PlayStation Network will be going offline again this week, for scheduled maintenance. The maintenance period will begin this Thursday (May 31st 2012), starting at 4:00pm BST and will last until Friday, 8:00am BST. The downtime will affect both North American and European regions.
As usual, all PSN related services will be offline during this time, but may still collect in-game trophies and they will be synched when the PSN is back up and running.