This is a boilerplate static app powered by middleman (for static site generation), a SASS port of Twitter bootstrap for a starting style, and Ember.js for a MVC-structured JS frontend.
Through middleman, it utilizes sprockets for its asset pipeline (like Rails 3.1 does), so it concatenates and minifies the JS placed in source/javascripts. Middleman will also compiles down higher level languages like CoffeeScript and SASS.
Relevant links: Ember.js rasputin middleman bootstrap-sass