So as much as this isn't much of an exploit as so far I have found quite a few people using this method, I know it's a very fast way to level if you can get the mats - from playing the beta by handing in "Bundle of Groceries" for the quest "Replenishing the Pantry" in Valley of the four winds given by Nam Ironpaw in Halfhill you get maybe 1k or so per turn in.
If you haven't started already you should try get a hold of a nice amount of the mats and level very quickly like I plan to when we hit live
not 100% sure this will work when we go live but it was working fine on the beta