If you start X with startx, the permissions on /dev/console will not get changed, resulting in things like xterm -C and xconsole not working.
This is because of the way console permissions are set by default. On a multi-user system, one does not necessarily want just any user to be able to write on the system console. For users who are logging directly onto a machine with a VTY, the fbtab(5) file exists to solve such problems.
In a nutshell, make sure an uncommented line of the form
/dev/ttyv0 0600 /dev/console
is in /etc/fbtab (see fbtab(5)) and it will ensure that whomever logs in on /dev/ttyv0 will own the console.