Okay, how did we miss this?
We've been wondering about the level of change in each old-world zone for Cataclysm for months now, and the answer has actually been under our noses since BlizzCon. During the Art Panel, the above planning map was shown, along with some information to either side of it. We can't make out everything in it, but there's a lot of information if you know what you're looking at.
The zone colors, from what we can infer, indicate the level of overhaul each zone is receiving. Red is a heavy overhaul, yellow is moderate, green is light, and blue means a brand-new zone. The yellow stars indicate a dungeon, and the red stars indicate a raid. The white tabs each have a letter on them, indicating what in the zone was being changed at that particular point -- L for level, Q for quests, etc.
Astute readers will see some things jump out at them immediately, like Thousand Needles having two stars on it.
The full list of visible zone changes after the break, along with other pertinent info.
Disclaimer: While this image was captured during the BlizzCon 2009 Art Panel, the capture displays a photo taken by Blizzard staff, which is undated. We don't know if it was a day before BlizzCon 2009 or six months before. Things could have changed between when this picture was taken and when this article was published.