Not one rig. A -LOT- of rigs running multiple GPUs per rig. You can get about 3.5MH/s out of 1 rig if you know what you're doing (maybe more if you're using 4U rackmounts). So that'd be about 27 or 28 rigs if it were just normal motherboards and GPUs and not a giant rackmount. Not even sure ATI drivers could support a 4U rackmount honestly.
The guy is probably making good money still, but the electrical costs would also be enormous.
thats makes sense - at current exchange rates its about $239,045.80 usd a year - so not bad