Yep, last week most realms had rolling restarts, which means that this week we have a regular maintenance. This week all US realms (which means AU realms, as well) will have a regularly scheduled maintenance period, starting at 5:00 AM PDT and ending at 11:00 AM PDT. Sure, on good weeks, the realms can come back up early, but it's just as common for them to come back up late. So for those of you who usually play during this period of time, my apologies -- maybe you can join me in my downtime hobby of re-playing the original StarCraft!
[Information via the login screen -- nope, there's nothing on the official site, or I'd link it]