Yeah, I definitely want to find more places to use event listeners (beyond the built-in ones -- for saving, etc -- we can make up our own!), because it allows things to be more "loosely coupled". I've never really used signals in Django, but the pattern is very familiar to me from JS-land events (e.g. Backbone et al uses this for nice decoupling).

In this case, the `FacilityUser` already depends on `CachedPassword` explicitly (for the `check_password` stuff), so I don't see that we would gain much by using signals, but I'm probably missing something, too (again, I haven't really used Django signals before).