There's an even easier way to do static sites on heroku and have them compiled for you - use stasis (http://stasis.me) - I've built a framework on top of stasis and have been using it for months, as part of very large production sites, and it's been extremely stable and super easy to use.

All you need to do to get them working on heroku is include a super basic config.ru file, and you're all set. The files compile into a public folder which heroku uses to serve them.