Apple is now selling the rack mountable Mac Pro with pricing starting at $6499 (compared to $5,999 for the non-rackmountable model).
It sports the same build to order components as the regular Mac Pro, but has rack mounting rails that ship in a separate box. The base model comes with: 3.5GHz 8‑core Intel Xeon W processor, Turbo Boost up to 4.0GHz; 32GB (4x8GB) of DDR4 ECC memory; Radeon Pro 580X with 8GB of GDDR5 memory; 256GB SSD storage; Magic Mouse 2; and Magic Keyboard with Numeric Keypad.