I remember 10+ years ago at my first job we had a nice office building (it was an architectural CAD software company, so their offices were pretty okay). It was 4-6 people per room. In retrospect I wouldn't want that layout again, it kills XFN cooperation, eg. you have to go to another room and potentially knock just to talk to the UX or PM guy.
I prefer o.o. because it's better for fast moving, constantly changing teams building product; everybody's on the same "floor", working on the same product.