Sony sent this message out about PSN being down tomorrow:
PlayStation Network will undergo maintenance tomorrow, October 28. Maintenance is expected to start at just after 7:00 am Pacific and will last for several hours, until approximately 3:30 pm Pacific. During this time, users won’t be able to access the PlayStation Store, PlayStation Home or Account Management, and may encounter difficulty while signing in to PSN.
Tags: PS3, PSN, Sony