Sneazr is a super simple plugin for Nose that adds Growl notifications.
First you need Growl installed and you will need to install their python library. For instructions on installing Growl's python library, see their documentation.
After that it should be as easy as
easy_install sneazr
After installation you can do..
nosetests --with-sneazr
..and a summary of its results will be spit out through Growl. Happy Days!
For instructions on using it with watchr to get continuous testing behaviour check out this post