Sony has announced on its EU PlayStation Blog that the PSN will be offline for a brief period due to maintenance.
The PlayStation Network will be offline from 16:05 on Thursday 11 August 2011 until 02:00 on Friday 12 August 2011, BST.
This will prevent you from accessing the PlayStation Store on both PS3 and PSP and also your PSN account.
Countries that will be effected by the maintenance includes, Arab Emirates, Australia, Great Britain, Israel and New Zealand.