What do you mean for physical console? In bash you can set the TIMEOUT for a session by the environment variable TMOUT, for example if you open a terminal and issue
the session will end and the terminal will close after 5 minutes of inactivity. You can set the variable in .bashrc for root and the trick is done.
In KDE you can also setup a timeout for the X session. Since KDE 3.4 this is a feature of the screensaver. You have to edit the file $HOME/.kde/share/config/kdesktoprc and under the screen-saver section add
Code:
AutoLogout=true
AutoLogoutTimeout=300
I don't know for GNOME sessions or for other desktop managers, but maybe there is a similar feature.