I assume you are talking about his wiki page: http://wiki.dreamhost.com/Discussion_Lists
That page is written for those using dreamhost email for there domain, although that is not stated (it probably should be).
I wonder if the mailman discussion lists setup in the dreamhost panel even works when your email is hosted with google? I don’t know. It would certainly seem like there would be some actions that would need to be performed on the google side.