Will World of Warcrafts new expansion Cataclysm require any of the previous expansions

when cataclysm is released, the geography of the original game will change permanently. this means that even if you don't purchase the expansion you'll still be able to see the changes. however, you will not be able to use any new content that comes out with cataclysm, such as the two new races (worgen and goblin)