I just stumbled over your post by incident. I am very interested in your ideas about a Java ME rich client for Moodle. Actually, I am working on such a client for quite a time now. It is a hybrid architecture, combining both the advantages of a rich client and mobile web. There is also support for context aware activities via mobile tags (and GPS support will follow in the next few weeks). I hope to be able to publish the output here soon. At the moment I am refactoring my code to suite new Moodle 1.8 version. You are welcome to have a visit at http://www.mobileclassroom.at whereas I do not have rich documentation yet and the site is german only
Regards, Andreas