Eyonix from Blizzard let everyone know about the following changes during todays sevice schedule.

We will be extending tomorrow's (Tuesday, August 22) normally scheduled realm maintenance by approximately two hours. The additional time will allow for the application of a patch. The maintenance time will run from 3:00 AM PDT to 11:00 AM PDT. In addition, the following realms will be coming down tonight at 11:00 PM PDT in order to begin the retrofitting upgrade process, which will provide substantial improvements to individual realm performance. These realms are scheduled to be brought back up tomorrow morning, once the normal maintenance concludes.

Aggramar | Argent Dawn | Arthas | Azgalor | Bleeding Hollow | Bloodhoof | Burning Blade | Burning Legion | Durotan
Earthen Ring | Elune | Eonar | Eredar | Gilneas | Gorefiend | Kargath | Laughing Skull | Lightning's Blade | Llane | Lothar | Magtheridon | Malygos | Mannoroth | Medivh | Shadow Moon | Shattered Hand | Skullcrusher | Stormrage | Thunderhorn | Thunderlord | Warsong | Zul'jin