So just like before WotLK came out, if you zoom out of the map all the way, you can see some islands that will be added in the next expansion. For WotLK you could see Northrend, and now with Cataclysm you can see... I have no idea what they are called but they are islands that don't show up when you click on Azeroth.
PRETTY COOL RIGHT? I was shitted my pants over this.
EDIT: Not sure if they were there from before WotLK as well... But I don't remember. There. Just in case it was in before WotLK, then I totally said it before anyone else posted flame comments saying that I'm teh stupid for not noticing it before or remembering it, and I get to keep my ego.