Javageomodel is a project mainly written in Java, it's free.
javageomodel decoupled from JPA
This project is a fork of http://code.google.com/p/javageomodel/ If you intend to use GeoModel with Objectify, check this post: http://brunofuster.wordpress.com/2010/09/21/javageomodel-with-objectify/
any doubts/ideias, please send to brunofuster at gmail