The information pulled from the alpha client includes maps of several of the new zones, including a peek at the newly-terraformed Azshara, Blasted Lands, Gilneas and Hyjal. Also included are various NPC models including the Deathwing model featured the other day; and a host of various critters and items that will be found in Cataclysm. Boubouille has noted that the post containing all of this information is still currently being updated, however there are plenty of screenshots to look at already.
The most interesting information has nothing to do with screenshots or images: the new talent calculators are available as well. While these do not appear to reflect all of the changes coming in Cataclysm (hunters still appear to have mana-based talents and skills), there are new talents in the trees that were not mentioned in the Cataclysm class previews from last month. All in all, a wealth of new information to be pored over and analyzed -- but keep in mind, these are from the alpha build of the expansion, and will likely receive several revisions between now and release.