Re: OS X Server
OS/2 and Windows could do that all years (1990) before OS X was a twinkling in Apple's eye. Granted, in the early days it required a special NIC PROM and used RPL rather than PXE, but it did work. Of course the difference was that Mac hardware is much more standardised than PC hardware.
Boot times weren't horrendous, but swapping over the network wasn't a good idea..