US Company H Squared who already make some cool rack mounts for the Mac Mini are just about to release a rack mount kit that will take up to six new Mac Pros
You're probably still waiting for just one Mac Pro to arrive but if you had to put six in your machine room this would be a cool way to mount them.
US company H Squared are prototyping a rack mount shelf that will hold up to six new mac Pro's with integrated cabling and airflow. It looks sweet. I wonder if they will do one that hangs on the wall?
If you had the 12 core Xeon versions that would give you 72 cores in just 6U: not bad for a render farm.
There is no news on release dates or pricing yet but their Mac Mini rack mount sells for $299