I don't know, perhaps I'm blind and oversee something. (Tell me someone, if that's the case, please!)
But if I'm at the "groups" page I'd like to see some kind of "about" link or so. I can't find anything on the "help" page that explains the system, either.
For example: I joined the group "Neighbors On Lethensome Lift", because I own a house there. It says "anyone can join" this group, but when I click on it, it says "You do not have permission to view this group's discussions." --> Is it, because someone has to confirm my participation before I can read the discussions? Anyway, THAT is a question I'd like to get answered somewhere.