Yeah, they changed the wording of a few things and added in some confirmation boxes to make the process a bit easier. I'd pull the exact info from the Blizzard thread, but at the moment it looks as if a million subscribers have all decended on the Blizzard forums at once
Basically thats the same old checkbox, but with a different label. Also, from memory, on the next patch you will get a confirmation box stating that some of your interface files may be out of date.. do you want to load them anyway? Just say yes and it'll load them up.