The first motherboard specifically designed for mining has been released:
It's got support for up to 12 (TWELVE!) GPUs through the most unique PCIe layout's I've ever seen:
The price and release date are still TBD, but I'm going to strongly look into this board to power a GPU focused build!
What do you think about using this as a platform?
Source: Anandtech (http://www.anandtech.com/show/11604/biostar-mining-tb250-btc-pro-motherboard-rx-470d-gpu)