David's revised DMX Server uses D-Bus for configuration, added Composite support, provides X-Video support, adds in RandR 1.2 support, and a few other notable changes.
The Distributed Multi-head X server was originally designed to be a proxy server that in turn interfaces with one or more X Servers that aren't necessarily running on the same physical computer. With David Reveman's latest work is to use DMX (also known as Xdmx) as a proxy server on virtual machines and remote desktops. A VNC viewer is then able to connect directly to the DMX Server.
Additional details on this work can be found on the X.Org mailing list.