I have the same problem but I cant solve it :/
after the update to the latest xbmc version of stephan, HDMi CEC isnt working anymore.
I got the same error messages, applied the udev rules and the usermod thing.
now there are no more error messages in xbmc.log but HDMI-cec isnt working -.-
what could be the problem?
I can remote my TV from cec-client but I cant remote XBMC with my TV.