CAPRICORN TECHNOLOGIES just released a low power, fairly intelligent storage system based on the Via mini-ITX boards. The short story is 3TB per 1U node, 120TB per 19 inch rack.

I first saw these boxes at the Via restaurant last CES, or maybe two CESes ago, either way, I was fairly impressed. What they do it take a low power mini-ITX board running at 1GHz, stuff some RAM in, and then add four hard drives. To get the maximum density, you then slap it all into a 1U case. When you have a wall of drives, things get hot fast, and the less power you use, the less you have to pay for, and to dissipate which is why a Via solution is far better than a Tulsa here.