World of Warcraft: Cataclysm Previews

Not only has G4 whipped up a three-minute preview of the expansion's storyline, but there's also a text preview of World of Warcraft: Cataclysm available over at Gamespiral. Some zone-by-zone changes:
Orgrimmar: The main changes in Orgrimmar are to allow for flying mounts. There will also be some aesthetic changes including the city having an iron facelift to replace some of the stone walls. A sign that the war has stepped up a gear. Blizzard have hinted at new NPC's and some current NPC's, such as Thrall, leaving.

Stormwind: Again most of the changes to the Alliance stronghold will be to allow for flying mounts. What this actually means is not clear yet, we can assume there needs to be some high points for flying mounts to land, but that is just speculation at the moment.

The Barrens: This represents one of the biggest changes to the World of Warcraft, with the region about to be split in two by a volcanic rift. This may mean that many current quest chains are lost forever.

Auberdine: Another big change, Auberdine is going to be destroyed completely. This may come to a shock to anyone with a Night Elf character as this was one of the first big towns for a starting Night Elf. Blizzard have said it will still be visitable, but presumably juts as ruins. Night Elves will get a new location in northern Darkshore.