The PlayStation Network will be down tomorrow for 14 hours for routine maintenance. Unfortunately it will be taking place in middle of the day, instead of at night! You will have to find something else to do tomorrow during hte hours of 8am to 10pm Pacific.
You will not be able to access anything on the PlayStation Store from a PS3 or PSP. That includes access to the PSN account management, and PSN account registration. In addition, the ability to log in from the U.S. PlayStation website will also be restricted. There may be some lucky users that still manage to get online, but the vast majority of people will have no access.
Dear Sony, please do maintenance on off-peak times (at night).