However, I will chime in with a reccomendation... the following is always the last item I see on messages I get from the Galileo mailing list- I think it is very helpful and not at all intrusive to include this information with every message.
It's actually standard on all the other lists where I'm subscribed. I would highly recommend adding such a (perhaps *very* short message) to each mail from the list even though that does not prevent people from asking how to unsubscribe (at least not on the OpenGL game developers list ;-)
Andreas