We've been hosting Mac minis for 9 years now. They are incredible machines but we're going to branch out a little. Today we also offer colocation of the new Mac Pro. This service can be found at MacProColo.net.
We tested the Mac Pro quite a bit in the data center. It performs incredible and there is no issue with heat. The Pro does pull quite a bit more power though. (And in a data center, power is one of the biggest expenses.)
For most people, the Mac mini will easily do the job and will also be less expensive for purchase and for colocation. In my opinion, I think most people will want the Mac Pro on their desk and the Mac mini in the data center.
But for those who do need the power of a new Mac Pro, we're happy to offer you a spot in one of the best data centers in the world.