D800: what's the point?

Just like a Medium Format camera, if you have to ask (and you do) then it is not for you.

For those of us for whom it makes sense, there is not, nor has there ever been a better DSLR.

You should put a MF Raw 100% crop at even 800 ISO next to these, then you'd be really confused as to why anyone would spend $30,000 on such a camera.