I met a player in the beta a few nights ago riding one of the brand-new Engineering ground mounts, and he was kind enough to pose for a few pictures and chat with me about it. At the time he confirmed that the mount was being sold in Dalaran for a fraction of its actual value, presumably for the sake of testing its passenger function (which unfortunately still seems to be bugged, so don't count on hauling a buddy along if you run out and buy one right now). He also said the mount was BoE, which both I and Alex had a hard time believing would remain a permanent feature. Blizzard seems to keep most engineering gewgaws in the family, as it were.
Well, it looks like we were wrong; CM Valnoth has confirmed that the new Engineering-made ground mount for Wrath is going to be Bind on Equip, so I'd advise making friends with a good Engineer sometime soon (by the way, don't miss Jaylynn's #68 comment on the next page of the thread). We're not sure how expensive the mats are going to be once Wrath goes live, although the player I spoke to estimated it would be less than the current cost of a Turbo-Charged Flying Machine (though quite likely to be more expensive before the Northrend-fueled economy settles somewhat). Daniel Whitcomb's also observed it's likely to remain BoE as having one of these babies is linked to the achievement Get to the Choppa!, so with any luck Engineering is going to be a somewhat more lucrative profession in the expansion.