It is packaged as a grunt plugin and provides you a bunch of tasks and helpers to help improve the performance of your site/app in a production environment.
This node/grunt-based build script tries to be as close as possible to the ant-build-script, a really great project you should check out.
It is still in early stage of development, but it'll get better and better, based on your feedbacks.
Fancy one line install:
# see the gist: https://gist.github.com/2359881 $ curl https://raw.github.com/gist/2359881/install.sh | sh
Slightly less fancier
$ npm install https://github.com/h5bp/node-build-script/tarball/master -g $ h5bp help $ h5bp init