SerfJ 0.3.0 released! A new MVC framework for REST applications
Apart from serving .JSP or .HTML pages, controller's methods are able to return serialized objects as JSON or XML, although developers are free to develop their own serializers (XML, JSON, CSV, or whatever they need).
This project is opensource under Apache 2.0 license, hosted at Sourceforge. Also its artifacts can be found in Maven Central repository.
You can find more information about how to use it at http://serfj.sourceforge.net, the development team is looking forward to getting your feedback.