Ahh, well my use case is that I have a private club that likes to talk private club stuff. Currently we are on a mailing list (I was using mailman, now I am using the paid version of google groups which is like mailman more or less).
I would like to point people over to this new thing at least just to try out. Our group isn't that big so I can just get people to log in and then add them, but I think it is a valid use case.
Even invites for non private forums seem like they would be a good thing to get people over here.
Also, in addition, I have been logged out for some reason a few times today in chrome without closing the browser or even the tab.