This is a Heroku buildpack for nginx. A dyno created with this buildpack will assume anything deployed is an nginx app. Any of the files in the compile step can be overriden by the deployed app so that you can define a custom nginx conf.
This is just for serving static files or proxying, check out the other nginx build packs for proxying via a local socket to a backend started with nginx.
The nginx binary is latest stable verion 1.8.0 built on the heroku cedar-14 stack using yappbox/yapp-native-build.
To update nginx just copy the binary built on heroku following the README
yappbox/yapp-native-build
to bin/nginx