App Engine Frameworks
Here's a (somewhat complete) list of App Engine frameworks for Python. Please leave a comment to have others listed.
App Engine specific
Frameworks designed specifically for App Engine. * GAEO * GAE Framework * Kay (also based on Werkzeug and Jinja2) * MVCEngine * tipfy (oh yeah, we love it!) * webapp * webapp2
App Engine featured
Frameworks not designed specifically for App Engine, but which contain App Engine features. * Glashammer (also based on Werkzeug and Jinja2) * pyxer
App Engine ported
Existing frameworks ported to App Engine. * App Engine Patch * Django-nonrel
Other frameworks
Other frameworks that should play nicely with App Engine architecture. * BFG * Bottle * Flask (also based on Werkzeug and Jinja2) * Tornado * web2py * web.py