The Google FeedServer is an open-source Atom Publishing provider based on the Abdera Framework. Google FeedServer implements simple backend data adapters that allow the developer to quickly deploy a feed for an existing data source such as a database. The FeedSever makes it easy to create these adapters.
The home of the project is at:
http://code.google.com/p/google-feedserver/
There, you'll find links to Abdera as well as more reading material in the Wiki. For example, an overview of the project is at: