Never mind the fact that last week, in the lead-up to Sony's Gamescom press conference, the PlayStation Network went down for maintenance. This week, it's going down again!
At 2.15pm (PST) tomorrow, August 25 (which was 8am today AEST) and running for around four hours, nobody will be able to sign into the PlayStation Network to do anything. Downloads, games, whatever. You'll be locked out.
On the bright side, it's not a total lockdown; Sony say that if you're already signed in before 2.15pm (PST) and stay signed in, you'll be able to stay connected throughout the downtime.