[[Please note that Github has changed a lot since this question was first asked; instead of \"download page\" read \"new release\".]]
I generate PDF documentation as par
Github API v3 supports this feature.
GitHub also provides a maven plugin based on the java API that is part of the Eclipse Mylyn connector for GitHub.
There is a ruby gem called github_api.
The other answer talks about net-github-upload which is available for perl and ruby.