One of the impressive features in Comfortable Mexican Sofa is editing js and stylesheets online. There is no need to deploy each time the assets are changed. I suppose javascript and stylesheets code is stored in database.
I am curious if those assets are precompiled and served by the pipeline, like regular assets in a Rails application?
They are served as a normal controller/action response. Run rake routes and take a look at cms_content_css and cms_content_js paths. So there's an overhead compared to serving precompiled assets. This is not an issue with relatively low traffic sites, but when server load is a concern you probably want to implement some sort of caching.