Allows you to setup continuous integration without any external software. Just a checkout of your application from Subversion and a call in the post-commit hook is needed. Install with:
svn export http://dev.rubyonrails.com/svn/rails/plugins/continuous_builder
…or start out by reading the source. Created by Tobias Lütke and DavidHeinemeierHansson.
A pretty lengthy explanation of how to install and use the plugin can be found here: http://www.ryandaigle.com/articles/2006/05/24/continuous-integration-w-rails
See also Plugins