Sony will be taking the PlayStation Network offline for two hours tonight to perform routine maintenance, according to the PlayStation forums.
The network will go down from 9:30-11:30 p.m. PT. As disruptions go, it should be a relatively pain-free one: Sony says that even during the two-hour window, any PSN user will still be able to sign in, play games and use "most applications." However, neither the PlayStation Store nor PlayStation Video will be available, and users won't be able to access account management, either.
Sony recommends that PlayStation 4 owners activate a particular system as their primary console before the maintenance begins, so they'll be able to keep using the system during the maintenance period. All platforms that use the PSN will be affected, including the PlayStation 3, PlayStation Vita and Sony's websites.