Xorg is in the process of moving away from the old xorg.conf configuration system to a dynamic one based on hal policies and other automatic techniques, and I believe it now uses the evdev driver for most input devices. My new xorg.conf on one of my systems contains only three active lines, in fact.
I also noticed that evdev generates different key codes than the older drivers. I couldn't tell you what is defining the actions bound to yours, but I'd assume it's kde, either through hotkeys or input actions. It probably has actions predefined for some of the more common multimedia keys, such as the sound controls.
If all the buttons are defined with keysyms (names like "xf86AudioMute", xev will show you) then you should be able to use them the same as any other key in your kde hotkey definitions and such, or you can always continue to use xbindkeys.
If any of them don't have keysyms (but do have keycodes), then you can use xmodmap to assign keysyms to them.
Last edited by David the H.; 07-26-2009 at 12:04 PM.