According Isradun, multiple realms are being restarted now. There are additional posts on the WoW Realm Status forums that indicate they've already been at this for a while. However, as I've tested, no fix appears to be working perfectly yet.
We'll keep this post updated for you with the latest.
Update, 12:05 a.m. EST: Apparently the realm issues are subsiding, although no Blizzard update yet. Some reports are still trickling in of issues in the Nightfall and Reckoning battlegroups.
Update, 12:18 a.m. EST: Blizzard saw what I said and decided to start crashing realms again. Multiple Tech Support Forum posts report things are not well, again.
Update, 1:08 a.m. EST: Everything appears to be working now. Blizzard has removed the opening announcement, and the spam on the forums has quited down. Enjoy the night!