I wanted to generate Growl notifications from a Ruby script on OSX and had a bit of trouble getting it to work. To save you the same hassle, here's the steps I took:
Install Growl if you haven't already. I used version 1.2.
In the growl preference plane (find it under System Preferences)
There's a couple of different ruby bindings for Growl but ruby-growl seemed to work for me
gem install ruby-growl
You can now send notifications from Ruby
require 'rubygems' require 'ruby-growl' g = Growl.new "127.0.0.1", "ruby-growl", ["ruby-growl Notification"] g.notify "ruby-growl Notification", "It Came From Ruby-Growl", "Greetings!"