In message <3536384F.5694@santa.asf.alaska.edu>, Robert Alexander Baxter writes
:
>Perhaps you could use xkibitz, which comes with expect.
>It is intended to be used as a multi-user terminal session

FreeBSD ships with watch(8).  I don't know if it's available anywhere 
else.

WATCH(8)                FreeBSD System Manager's Manual               WATCH(8)

NAME
     watch - snoop on another tty line

SYNOPSIS
     watch [-ciotnW] tty

DESCRIPTION
     Watch allows the superuser to examine all data coming through a specified
     tty.  Watch writes to standard output.