This Wired article indicates a demand for rack-mountable Macs.
Researchers are increasingly hooking up ordinary PCs into clusters to make cut-price supercomputers. But to do so, the hardware must come in "rack-mountable" boxes that can be stacked floor to ceiling in specially made racks.
This reflects a number of predictions that have sprung up over the years that Apple may revamp it's server line with a rackmount design. If Apple is serious about winning over the server/biotech market it seems a natural fit...