If your realm is offline, I suggest reading up on everything in WoW.com's Guide to Patch 3.2.2. At least that way you'll be prepared for Ony when the time comes.
The full list of realms undergoing extended maintenance after the break.
Update 12:20 p.m. PDT: Most realms are now coming back online.
Offline until at least 12:30 p.m. PDT:
- Scarlet Crusade
- Shadow Council