Looks like all the bad weather the people in the southern states are suffering through is having some effect on the beta servers and the network. Blizzard had the following to say regarding the situation.
Emergency Update: Extended Server Downtime
Due to a recent tornado-related emergency, our US servers for the World of Warcraft beta test have been taken offline and will remain offline through the night and into Saturday. Please check back here tomorrow afternoon for a status update. Thanks for your patience and understanding; we are working to restore service as soon as possible.