Servers will be going down on June 18th for about 2 hours, starting at 9 AM Central Time. (16:00-18:00 CET) Game Update 1.2.1 will be rolled out and includes some fixes and updates for future content (the Cataclysm). Patch notes can be found below.
Below are the update notes for patch 1.1.1, which will be rolling out tomorrow (May 7th) at 10am Central Time. There will be no down time associated with this update, however you will need to close the game to download the patch.