Here's how I understand this: 
If a file is requested (over an $http call or browser/curl request) with .ng at the end, then the haml template gets rendered but without the base layout file (just the file at that location with the partials it calls).

This means that our application directory structure will be using the traditional location of rails views but typically the views will be used by angular without the layout (layout will only get loaded on the initial GET request to app).