A Central Authentication Service (CAS) implementation for Google App Engine
This implementation is focused on the use of the CAS with a third-party service, who whants to authenticate its user with a CAS server
A demo can be found on this website
The appengine implementation on a development environment (your computer) seems to retain some cookies and prevent this implementation to work properly.
But on a (pre)production environment (while deploying to appengine), this issue doesn't occur.