It is a fairly new thing.
The problem I always had with memdisk and floppy images was that different vendors handled the pxe stacks differently. Many of my intel machines would work fine, some needed other options to work, and some wouldn’t work at all. From all the reading at the time (this has been a few years back) all the problems were because there is no good pxe standard. I haven’t used it much but gPXE (or is it iPXE now?) might be the first thing you want to load, then pass your other pxe options to it, you will probably get better results that way. From my limited knowledge of this you would probably want to chainload it (according to the ipxe.org website),
[SIZE=4][B][FONT=Lucida Grande][SIZE=18px][COLOR=#000000]Chainloading from an existing PXE ROM[/COLOR][/SIZE][/FONT][/B][/SIZE]
You can chainload iPXE from an existing PXE ROM. This is useful if you have a large number of machines that you want to be able to boot using iPXE, but you do not want to reflash the network card on each individual machine.
You can build a chainloadable iPXE image using:
[SIZE=12px] make bin/undionly.kpxe[/SIZE][/COLOR][/FONT]