Martin Peres and I made a quite long talk about the X.org security at XDC 2012 in Nuremberg.
Michael Kerrisk made a really good article for LWN.
Right after this talk, we had an interesting conversation with Kristian Høgsberg and Daniel Vetter which led to ideas to rework some parts of
DRM to fix both security and usage problems. The slides and the video for the second talk we gave at XDC 2012 are also available for download. The YouTube hosted video is embedded below and the short summary is available too.