Exactly. A preview, but with the option of giving instant feedback, thus altering it before press time. I know other game systems have something like "the living rules", which I think is what they have for the Mordheim game, but this seems like something altogether different.
I think Thom should keep droppin' the revised rules on us, so we can all throw the tough questions at'em, and keep the new troops and stuff, and of course the fiction (which drives this game like crazy) for when it's released.