In a nutshell

ao.shorturl is a library for integrating short URLs to a web application. Its front-end configuration is not specific to any web application framework, instead it uses various back-ends for different frameworks.

For example, ao.shorturl.appengine implements a Datastore backand for Google / Typhoon App Engine. If installed as a Django application, ao.shorturl also provides a template tag for easily displaying short URLs for any object that supports them.