You could always buy it separately, $499 for unlimited clients. There's now a "Mac Pro Server" option available, which includes OS X Server, but is priced a bi

You could always buy it separately, $499 for unlimited clients. There's now a "Mac Pro Server" option available, which includes OS X Server, but is priced a bit lower than if you take the base Mac Pro and configure it with the same hardware but without OS X Server. (Take the base Mac Pro, raise the RAM from 3GB to 8, add a second 1TB hard drive, and you've got the same hardware config as the Mac Pro Server, for about $30 more, and without OS X Server, which would add another $499 to the price.)