Basically it's a Google Chart API clone using JFreeChart. Well calling it clone may be an understatement as this is a really cool project.
Anyway I have applied for a plugin developer account and so I hope to be able to upload to the repository soon, and in the meanwhile you can find the plugin here.
For a quick test, once installed open this page, http://localhost:8080/app/plugins/eastwood-chart-0.1/test.gsp. You should see the actual graphs produced from Google Chart on the left and the Eastwood charts on the right side.
(Charts produced by Google Chart on left and Eastwood charts on right)
**UPDATES: File has been uploaded to the plugin repository. You can now install by the usual "grails install-plugin eastwood-chart". For more information go to the plugin page, http://grails.org/JFreeChart+Eastwood+Plugin.