The excerpt doesn't reveal any new lore per se, but it does tease pretty damn well, and should bring up some pretty nostalgic memories for a lot of Alliance players. Combine this with the excerpt from the manga, and you'll get a pretty good idea of where the story's going, I think -- Right into the Heart of the Emerald Nightmare, as we confirmed with authour Richard Knaak at BlizzCon a week ago.
As to whether it will cover the Cataclysm, or not, that's a bit up in the air. However, considering we know that Malfurion will be back in the waking world fighting Ragnaros at Hyjal, chances would seem to be good.
You can check out the excerpt at Simon and Schuster's website.