This plugin integrates RWT - the web-ported Standard Widget Toolkit (SWT) - into your Grails application. It enables you to build your RWT and JFace powered user interfaces using Groovy and the complete Grails framework stack with all its powerful features and syntactic DSL sugar.
The RWT plugin is available here: http://grails.org/plugin/rwt/
The documentation is available here: http://bwolff.github.com/grails-rwt/
A small example application that demonstrates the usage of the plugin is available here: https://github.com/bwolff/grails-rwt-example/