If you had plans to play any PS3 game with your best friend tomorrow you may have to make other arrangements, as Sony has announced that the PSN will be going down for quite some time on Thursday March 1st. The network will go down at 8:00 am PST and it wont come back up until 10:00 that night. If you live the UK the time converts to 16:00 to 6:00.
Normally during PSN maintenance you would be able to sign in before it began and still be logged in during the duration of the down time, however this time it is different. The PSN will be completely gone and it will sign out anyone online for the duration of the maintenance. All services will be inaccessible during the maintenance period including all PlayStation websites. So to know when it is all done keep your eye on the official PlayStation Twitter account.
