Raphael Stolt, with some time on his hands, set up a local copy of Xinc, the "shiny new Continuous Integration(CI) server" as hosted on the Google code site and spent some time working with it:

Since then the idea of building a Growl publisher plugin for Xinc was traveling my mind repeatedly, so the following post will break this circle and show a possible approach to build such a plugin, which can be used to notify the build result for continuously integrated projects and thereby provide an on-point/immediate feedback.

He includes the plugin class (ready for cut&paste) as well as the task definition and how to hook it all in to the Xinc build system. There's also a little example of it in action - a happy/sad indicator showing if the build failed or was a success, right there on the desktop.