To answer Atham's question fair and square; yes, three-way crossfire configurations exist. And on some chipsets, like the 790FX-based some time ago (2 years+), there were even opportunities for quadruple crossfire configurations (aka. Quadfire - ask Google!).
Problem is though, having 3/4 way crossfire conf. sometimes result in unsupported drivers etc. Many games prior to 2010 also do not support all "scaling" modes of a crossfire conf. - meaning that you do not get all the GPU "juice" from the cards in all games.
Add to that mixture the fact that the timings of common PCIe busses (x16 etc.) go down to low ones when running multiple graphics cards. The 790FX above could oftenmost only deliver 8x ; 8x ; 8x ; 8x when running four cards.
So even if 3+ configurations exist, they have still a long way to go.