Would you build an enterprise data center out of them?
Never.
Wrong hammer for the job - we agree on that. But nothing I saw on their online pages expected that the Mac Mini would ever stand up to the ultra high density server and storage solutions that exist now.
I thought the discussion was directed at small business security, not convincing Facebook to buy pallets of Mac Minis to stuff in their new Fort Worth data center.
I will say - with the proper software and ingenuity, a fanless SSD box like the Mac Mini could be ganged together to create such a monstrosity.
After all, even Saddam used PS2 units for missle or nuclear design.