oh wow. That is interesting. I'd buy it (for fanboy reasons if nothing else).
Will it be sold over impulse?
Does it have to be hardcover? those are expensive. Perhaps only a limited number of hardcover and a bunch of softcover (depending on how good the book is, of course)
Edit: Unless its one of those 3D pop-up books. You know, the kind we used to read as children (or at least I did). Those were awesome! They cost a lot, but are totally worth it.
Naturally that means a D&D, or other table-top RPG, will have at lesat a few games set in the world as well. (perhaps if I feel it is particularly well developed I could push Burning Wheel into posting something for it)
Is the book going to have a public beta too? You know, where we get to read it and correct typos or something?