Recently, the devs at Blizzard did some Q&A via twitter. Here are some interesting responses from the Cataclysm-specific questions:

Q. I'd like to see a new Isle of Quel'Danas-like daily quest hub in Cataclsym. One place, no travelling quick gold daily (: please?

We are planning to do exactly this for Tol Barad. When the battle is not taking place, players will be able to use the island as a daily quest hub. This will of course be very fun on PVP servers. =)

Q. With the advent of Heroic Shadowfang Keep and Heroic Deadmines, is there any likelihood of other older instances made Heroic?

A. Yes. We are hoping to do more than just these two, but it just comes down to time. We are focusing on getting the new Cataclysm dungeons done first and then we can look into doing more old-world Heroics.

Q. With the Lich King defeated, in Cataclysm, will the Plaguelands be green and beautiful again?

A. Western Plaguelands will finally be free of the plague in Cataclysm. It's hard for the Scourge to survive without their beloved Lich King. I guess this means we need to rename the zone?

Q. Will we be seeing more Caverns of Time in Cataclysm? War of the Ancients, maybe?

A. We will definitely see another trip to the Caverns of Time during Cataclsym. You are going to have to ask Chromie for more details though. =)

Q. Regarding Cataclysm, can you reveal any of the 'major changes' in Blasted Lands and how this will affect the lore?

A. I love the fact that one of our first questions is in regards to the Blasted Lands! We have big plans in store for this zone in Cataclysm. We will be revamping the entire flow of the zone so you can expect an entirely new experience here. Some of the big changes include an opening to the coastline for a new play area, as well as a large new worgen area in The Tainted Scar.