I’ve no idea who may have done this already, but I certainly coundn’t find anyone who had in five minutes of searching. I’ve written a Ruby port of Dean Edwards’ Packer, and released it as a Rails plugin. It includes a rake task for batch-processing the scripts in your application. Install like so:

ruby script/plugin install
    git://github.com/jcoglan/packr

More information on how to use it over here.