The Rails/Rack solution is rather complete (supports numerous sites), perhaps because the Rails community has smartly focused their energies on developing/supporting one project. Meanwhile, what I mostly find in the Django world are incomplete, cobbled-together solutions, each supporting perhaps a few APIs.
Am I missing a clear front-runner? Is there any interest out there in collaborating on a specific social networking authorization project to make it "the one" -- the Omniauth of the Django world?