There was a specific problem with exit which was fixed by Ted Tso's patch.
There _should_ be no other such problems, except perhaps users intentionally
leaving things running (or processes that do it themselves).
The other report I saw here (about needing ^Q) is indicating what is
probably a telnetd problem not resetting the terminal state cleanly.
Are these processes attached over tty/pty pairs, do their stdin/stdout point
to stuck tty/pty pairs, what telnetd are you using ?
Alan