A great Action Message Format (AMF) remoting kit for server side for the pythonistas is pyAMF, they recently released PyAMF 0.3 and have a sample running up on Google App Engine. There is also a tutorial for getting PyAMF running on Google App Engine. Aral Balkan got this running as well.

Features of pyAMF currently:

• AMF0 encoder/decoder for legacy Flash Players (version 6-8).
• AMF3 encoder/decoder for the new AMF format in Flash Player 9.
• Support for IExternalizable, ArrayCollection, ObjectProxy, ByteArray (with zlib support), RecordSet and RemoteObject
• Remoting gateways for Twisted, Django, TurboGears2, Web2Py, Pylons and any compatible WSGI framework.
• Authentication/setCredentials support
• Remoting client using httplib with authentication support
• Service Browser (DescribeService header) requests supported
• Local Shared Object (LSO) support
• Adapter Framework to integrate nicely with third-party Python projects

More on the PyAMF library:

• Download — Download PyAMF
• Examples — Tutorials and examples
• Features — PyAMF features
• Documentation – General documentation
• Mailing List — Join the mailinglist for user and developer discussions
• Blog — Announcements and news
• IRC Channel — Chat and discuss PyAMF or get support
• Success Stories — See how PyAMF is being used
• Team — The people working on this project
• License — The project is licensed under the open source MIT license