If you download the _Events.groovy script from the Osoco’s GitHub repository and put in in the scripts directory of your Grails project, you’ll get a nice bubble notifications on your Linux or Mac desktop.
This script requires libnotify (Linux) or Growl with growlnotify (Mac) installed. It assumes that GRAILS_HOME environment variable is correctly pointing to a Grails distribution (in order to display the Grails goblet icon in the notification bubble).
Credits to @deigote for the Mac adaptation.
Have a look at the Grom plugin I created for Grails ( http://grails.org/plugin/grom ) over a year ago which does exactly the things mentioned above on Mac, Linux and Windows.
Cheers, Jeroen