PlayStation Network is offline for scheduled maintenance from 16:00 on Tuesday 24 May 2011 until 00:00 on Wednesday 25 May 2011, GMT.
During the maintenance, you will be unable to access the following services:
  • PlayStation Store on PS3 and PSP.
  • PlayStation Network Account Management.
  • PlayStation Network Account Registration.
In addition, you will not be able to sign in to PlayStation Network from eu.playstation.com. If you wish to play online during the maintenance, please ensure you sign in to PSN before 16:00 on Tuesday 24 May 2011.
During this maintenance, you can continue to collect in-game trophies and these will be updated on your profile once PlayStation Network is back up and running.
If you have any questions about this down time, feel free to visit the official PlayStation Forums at community.eu.playstation.com where you can post your query and a member of the moderation team will get back to you.
source
http://ie.playstation.com/home/news/articles/detai​l/item284696/PlayStation-Network-scheduled-mainte...

this is more likely to get the store up and running for tomorrow