Blizzard posted the following two articles tonight to keep everyone up on what is happening with the beta servers.
Emergency Update: Current Server Status
At 6:19pm EDT yesterday, the datacenter complex in Virginia that is being used to host the World of Warcraft beta test was hit and damaged by a tornado. Because water was leaking into the building in which our servers were located, we shut down the servers as a precautionary measure and flew out a team of our network engineers to the location to survey the area and provide a preliminary assessment.
This morning, we have confirmed that some hardware has taken on water, so we will need to conduct a careful inspection for damage before we can restore power to the servers. This inspection will take 48 hours or longer to complete, so we encourage you to enjoy the rest of your weekend with other activities, as the World of Warcraft beta test will remain offline for at least that long. We will post another update tomorrow afternoon, and we appreciate your continued patience and support.
And
No US Patch Tonight
As mentioned in the news post below, we are working to try to make the US World of Warcraft beta patch available for download this weekend. The World of Warcraft beta game servers will remain offline for at least 48 hours as discussed above, but if we are able to provide the patch ahead of time, then when the game servers do eventually come back online, the plan is for players to already be patched up and ready to resume playing.
We will continue working on making the patch available, but we do want to let everyone know that this will not happen tonight. If you haven't checked them out already, the patch notes can be found here. Tomorrow afternoon we will post an update on the status of the beta game servers as well as on the patch.