It looks like Blizzard has their issues sorted out and the World of Warcraft site is now back online.
WorldofWarcraft.com Back Online
The site is back up and running. We apologize for the downtime overnight; we needed to take the website down for emergency maintenance. For those who missed it yesterday, the client is available for download to closed beta testers right here on the site -- just select the download link to the right, log in, and begin downloading. For additional information, please read our Final stress test FAQ and Open Beta FAQ.. Thank you for your patience, and welcome to the Final Stress Test!