On Windows, you should just need Growl for Windows.
Once you've got Growl set up, just add
barista_growl to your project's Gemfile and
bundle install. The relevant lines of your Gemfile might look like this
gem 'barista' gem 'barista_growl', :git => 'http://github.com/TrevorBurnham/barista_growl.git'
When you add
barista_growl to your project's Gemfile, the
[growl](http://github.com/visionmedia/growl/) gem will be added
automatically if not already present.
All source is available under the MIT license. See LICENSE for details.
barista_growl is pretty simple, but if you have ideas for improvement, just create an issue at http://github.com/TrevorBurnham/barista_growl/issues.