The PlayStation Network will be undergoing regular maintenance this coming Thursday, but it seems that this maintenance will be significantly more cumbersome than usual. On Thursday, March 1st, maintenance will start at 8am PST and last until 10pm PST. During this time, no users will be able to access the PlayStation Store, PlayStation Home, Account Management, or be able to sign into PSN. All users will be signed out once maintenance begins.
PSN enabled websites will also be down, such as the PlayStation Blog, but the PlayStation Twitter feed will keep you posted.
[Source: PlayStation Blog]