Sony says that the PlayStation Network will be down on March 1 for nearly a day to undergo maintenance.
Maintenance is expected to last from just after 8:00 am PST until approximately 10:00 pm PST. Below is Sony's full statement:
Unlike typical maintenance events, consumers who are already signed-in to PSN will be signed-out, and consumers will be unable to sign in for the duration of the maintenance window. During this time, users won’t be able to access the PlayStation Store, PlayStation Home, Account Management or play online.
PSN enabled websites will not be able to service users, including this one. Please stay tuned to the PlayStation Twitter feed for a notice when PSN is fully back online.
We apologize for any inconvenience this may cause.
[Source: PlayStation Blog]