In WoL, I get the original error
Game client mismatch with selected region.
The currently selected region may not be updated..."
before the login screen. I click OK and the login screen shows, normal except "us" appears in small white letters a little above the login box. From there I can log in normally. I didn't try WoL last night.
In heart of the swarm, I did not get that error last night, but I get it now. The "us" does not appear. After trying to log in, I get the second error
Your account has no game accounts that can be used in this region. Are you using the correct client?"
After clicking OK, it returns me to the login screen. Last night I did not have beta flagged until a little after this error was reported and then I received this error when trying to log in.
+1, exactly the same.
That US mark above the box is very interesting in particular, as it started appearing only a few days ago - right before the login/region problems started.
This is obviously some problem with global play implementation.