Fun little blue post.

"We're currently expecting both normal and rated battlegrounds to be cross-battlegroup (within a region) for the launch of Cataclysm. So, players queueing from anywhere in north america could play vs players on any north american battlegroup, etc."

This was a big issue for me. (you've likely heard me complain about this.)
Frankly I'm happy, I was pretty sure rated battlegrounds would be the death of WoW PvP.