Previously, the message was for toolkit, now it targets new upcoming developers… okay, if I’d be offensive I could say it targets vendor distributions which care for desktop on Linux :)
I have started hacking on X due the laboratory at my university I was working was running an amazing project to employ computer labs in all high-schools of the state I was living, in Brazil. It was a successful and all 2.100 schools used the multiseat computing model.
The beginning of my work in this project happened back in 2006 , and on that time I was trying to understand the situation that Linux using multiple graphics cards was living – that is only part of the needed work for making multiseat. The work proceeded but I never could actually push the patches to the mainline. Afterwards, and now at Nokia, I took this work again targeting some clean-up on X server code. It mostly went upstream (see VGA arbiter, libpciaccess and current xserver code). But the code is buggy and lot of work still needs to make it work properly.
Seems that I have a son now, but he (or should be she?) is a rebel baby and generates lot of trouble. Rather, I’m mean and want to give he away!
I don’t care about multi-card development nowadays and for an unknown reason no one also cares. But people use a lot: try to mix old graphics cards with new cards…. boom! Try to use multi-card with decent hw acceleration… boom! Try to hotplug graphics devices… no way! Hotswitch… hardly! Perform close to a single-card system… only in your dream! Some guys are kindly contributing sending patches for a while and unfortunately our open-source community are lacking man-power to make it get reviewed properly and eventually land at upstream. So here’s your big chance:
 BTW, I found the first patch I sent for X. It dates back in April 2006 and was against Xgl, GLX backend. Very funny :)