[xmonad] Xdmx as a solution to the multiple graphics cards, > 2 monitor problem

As many of you may or may not know, X11 is terrible at handling more than 2 monitors. If you have 2 different graphics cards with 2 monitors each, they have to be separate X11 instances which means you can't share windows between all screens. Yuck. I have a GTX 480 & a GS 4800 and I can make local X11 servers run on both of them. Is it possible to have Xdmx connect to two or 3 local instances of X11? If so, then, I can have a triple display! I ask this here Xdmx lacks a mailing list.