There's no downtime this week. Blue poster Wymdar has announced that there will be no rolling restarts and no downtime for the majority of servers, with one exception: the Uther server will experience a quick restart in order to fix an issue with a boat.
So enjoy your uninterrupted playtime. Or, if you're at work or school during that time, be jealous that there's other people playing while you slave away. Then read WoW.com to take some of the pain away. But hey, look on the bright side. This means you have at least another week to get that Onyxia achievement or try to farm up a Foror's Compendium before Patch 3.2.2 hits.