Sorry, but I'm working in Cakefiles this week, and Cake is still one of my favorite bands, especially Fashion Nugget.
As you know, I'm a big fan of Coffee, HAML, and Less. However, I'm also a big fan of Require and Backbone. Now, it's true that Require can handle Coffeescript on the fly, but I'm also a firm believer in pre-compiling as much of my deployed assets as possible to reduce download and client pre-processing time. Sending the Coffee, Less, and HAML.js processors to the browser to make your life easier doesn't make the customer very happy. And r.js, the Require.JS compiler and optimizer, likes a specific layout in order to work well. So the solution is to mirror the ultimate layout in your js/css/html templates tree as coffee/less/haml templates, and then build them all into place.
The gist below is my first step toward doing this:
[gist id=2776520]
It's a fairly simple thing, but it accomplishes everything I care about. If you want to mirror your javascript libraries and images as well, you could build them with a 'cp' command to put them into the target directory automagically.