One thing that wasn't mentioned was template bundling with sprockets. A hack/workaround was posted at https://gist.github.com/989891 but I would really like to know if there is or will be a recommended way of doing it.
UPDATE: As much as I like Haml, I think I'll just switch to eco, since it seems better integrated for now, and... CoffeeScript! Now all I need is haml-coffeescript / eco-haml. Well it turns out this does exist: https://github.com/9elements/haml-coffee. But I don't know how much work I'd need to do to get it working with the sprockets asset pipeline?