Running demo is here: http://gwt-mvp4g-layouting-demo.appspot.com
Documentation is here: http://shamansir.github.com/gwt-mvp4g-layouting-demo/
mvp4glayout Library code is here: http://shamansir.github.com/gwt-mvp4g-layouting/ (Downloads are also there). To use a library you must have a compatible mvp4g version in your project and, currently, gwt-log.