After a few days of hard work from @argeus and me we decided to let the Grails Magnolia Plugin to the public. Much needed functionality works and internally we have started to develop new applications using it. Consider it a beta-release but it already brings a great CMS to Grails.
UPDATE: Check out the Quick-start guide.
Head over to to github.com/Bonheur/maglev/downloads to try it out yourself.