detail about how this is done

Not going in to detail about how this is done, but people have been able to exploit their way in to the new zones. This gives me the impression that the majority, if not all, of the data was implemented with 4.0.3a. Since that appears to be the case, and taking the no maintenance in to account, I would say that there will be no download or a very, wow or very small one to activate the data.