[silverlight]

I would think the main barrier to doing this is the tie-in between the hardware and software. Mac hardware doesn't even really have a "large server" piece. And certainly if they did it wouldn't be very cheap compared to a Linux box. Since basically any software you would run on OSX to run a server you would presumably be able to run on Linux as well (e.g. nginx, etc.), I don't know what the advantage would be.