Nice! I used to modify CPU coolers to fit them on my GPUs and they took out even more space than this 3 slot cooler
It won't be possible on a lot of mainboards, but I don't think you will need a 2nd 4870 X2 anyway and the scaling is crap.
Oh well, I guess people with enough money to buy two of these won't have a problem with getting a motherboard with the space for this either