'Aha' is a framework made specially for Google App Engine. Here are some quick instruction getting started with it.
You can get source code from the repository.
http://code.google.com/p/aha-gae/
Aha is a web application framework. It has been developed hoping it will be the best way to propagate your 'aha !' into the cloud :-).
Aha has following features.
Visit Quickstart for getting started playing with aha. Reading Tutorials would be the good guidance for you :-).