Edited by Kellestra on 2/11/13 7:12 PM (PST)
It couldn't be Authenticator-related, could it?
Edit: Never mind. A full client restart (That's logging out of the game completely, and starting it back up. Just to clarify.) seemed to fix the problem. the odd thing, is that it seems that other people aren't online even though they are. For instance, I was RPing with a friend. Bnet went down for us both, we talked for about a minute, then I just stopped seeing her posts. Thought I was being ignored...
I just had and fixed this error on my Macintosh.
I ran the World of Warcraft Launcher program and it updated itself and the main WoW program. I was then able to log in.
In fact every time I have had this issue on my Macintosh the solution has been run World of Warcraft Launcher, find out there was some form of update, apply it, and not have problems anymore.