This isn't so much a mapping of events to commands, but of the events triggered by commands to the methods that handle them in the view. So in my appLayout I have the following:

    contextEvents: {
      'show:home': 'showHome'
    }

showHome is the function that shows the HomeView in the contentRegion of my appLayout.

It's really only to clean up the Views initialize(), which would otherwise have a number of ```context.listen(this, <eventName>, <callback>);``` calls.