Oddly, I was able to log into WoW when the notice was first posted, but I can't anymore. I wasn't doing anything important, so I decided to check it out and sure thing, it was time for a ride on the failboat. I'm also stuck on a loading screen while trying to test out the Iron Council on the PTR, so I'm currently riding on a Cruise Failboat. How decadent!
If we get any other updates before the authentication server starts working again, we'll be sure to keep you all posted.
Edit: Welp, it (mostly) works again. Go forth and play (some of you)!