Sony are conducting some scheduled PSN maintenance this Thursday, here is a quote from the source:
We know that you’re all very excited to hear all of the exciting PlayStation news coming out of Gamescom. Be sure to keep your eyes to this blog all week for all of the stories, pictures and videos that will be coming to you directly from Europe.
In order to continue bringing you the best online games experience on PSN, we will perform routine maintenance beginning Thursday, August 22nd. This maintenance will start at approximately 12:00 Noon PT (1:00PM MT / 2:00PM CT / 3:00PM ET) and last until around 6:30PM PT (7:30PM MT / 8:30PM CT / 9:30PM ET). During the maintenance period, you may receive a maintenance notification when attempting to access PSN.
The PlayStation Store, PlayStation Home and Account Management will not be available during the maintenance period but you WILL be able to access online play and apps provided that you have signed in to the Network at some point between now and the time of the maintenance. So please be sure to sign in now if you wish to access the Network during Thursday’s maintenance window.
We apologize for any inconvenience this may cause and thank you for your support.