Thank goodness. I thought I had ended the beta for myself because I tried to go into a new area, I got a "You are not permitted in this realm," message, and then when I tried to log back in I got this error - so I thought I basically "beat" the beta and couldn't log in anymore.
Glad it's not just me.
I think the you are not permitted on this realm happens when they boot everyone off the realm first before shutting the server down. Cleans the server I guess so they can prepare for whatever work they are gonna do.