Clustergirls is a really simple app. Mindblowingly simple. It has few features (but some of them are really powerful!) and, at this point, is quite unlikely to be useful. It's designed to work well with Blender and ImageMagick but can easily be adapted to other software. It doesn't require a "master" machine or any direct traffic between the nodes, only a shared storage through which all communication is made. And it also has some error/failiure handling.
This application developed independently and shared under the GNU General Public Licence.