If you had big plans for this evening, you may want to reconsider. At the very least, raiders may want to wait until prime time has passed to give things a whirl. Generally, these things blow over as people start to log off for the evening, and there's less of a load on the server.
Blizzard is aware of the issue, so hopefully we'll see a fix for it all soon. I personally suspect it's unlikely things will magically get better tonight, but maybe before the weekend. That would be nice.