"Our goal is to fill shelves across the United States. Our goal is not to have empty shelves, it's to have full shelves. If we have empty shelves, that's one less consumer who could have bought a PlayStation 3," Tretton said.

and one less consumer who might be able to find a Wii on the shelf in that shelf space... which is the real reason why they want those shelves full of their expensive PS3's, just gathering dust... occupied shelf space can't be filled with competing products... hog more shelf space for your own products and consequently you leave less shelf space for your competitor's products... that's what marketing at the retail level is all about... occupying shelf space