"To facilitate that I want to make it easy to discover our modifications and pass them along to upstream and/or other consumers of a given upstream. One way to force this is to continue working with a upstream archive (tarball release, maybe a snapshot) and our modifications as patches."<p>It is interesting that Debian faces the same issues and has come up with the idea of using Git as a source package format: <a href="http://wiki.debian.org/GitSrc" rel="nofollow">http://wiki.debian.org/GitSrc</a>