I haven't really been involved in chat very much, but I was checking it out just now and it turns out I was made co-owner of a chat room! If I hadn't looked, I never would have known.
I think it would help a lot to get people involved in chat if these kinds of events are shown to users through the parent site (where the user is involved) in some way. Showing the event through the MultiCollider SuperDropdown™ would be even better because then the user would get the notification through any of the sites.
I'm not sure exactly how common these events are, so I'm hoping users with more chat experience than me will provide answers with proposals for rate-limiting, which events should be communicated, etc., or even thoughts on whether or not this is a good idea.