I'm not able to connect at all. Instant "You have been disconnected from the server." or just stuck on "Retrieving character list" screen.
I didn't touch settings or anything from last time I've played which was 12 hours ago.
Edit:
Connection to all of the WotLK realms is smooth as always. No problems there, only @MoP.
It seems that some people are having trouble to login. Yet the majority has no issues. I have not found anything odd myself.
I would like to ask you to try warmane's own MoP client and tell me if that allows you to log in.
If that is the case, please let me know which/whos client you are using so I can try and figure out what is causing these issues for some people.