I think all you guys opposed to kill or killall are just a little too windows brainwashed (sorry, that sounds mean but it's not meant to be) to belive that it's normal to kill a process. When your system does things it uses the same kill command, look at your shutdown scripts and see that they use kill or killall to stop things from running. I woudn't be surprised if "pressing the logoff button" in X simply runs a script that does something like "killall X", the same thing with CTRL-ALT-BKSPC it's probably just trapped by the keyboard handler and initiates a killall X. It's really normal in the *nix world and most programs are written in a way that they know how to properly close themselves down when you send them a kill signal.