Here’s a link to Ruby CI apps:
http://www.degrunt.net/articles/2006/08/27/cerberus-continious-integration-for-rails/
- Cerberus
- Damage Control – defunct?
- CruiseControl.rb
- Continuous Builder
More links:
http://www.degrunt.net/articles/2006/08/27/cerberus-continious-integration-for-rails/
http://www.cuberick.com/2006/09/continuous-integration-for-ruby.html
http://confluence.public.thoughtworks.org/display/CC/CI+Feature+Matrix
http://rossniemi.files.wordpress.com/2007/03/ci-ruby-on-rails-1_0.pdf
Also look at CI::Reporter to convert Rake output Rspec and Test::Unit to a format Ant’s JUnitReport can handle. That opens up potential use of the Java CI servers and CruiseControl.NET
http://blog.huikau.com/2008/01/09/jruby-ruby-continuous-integration-with-hudson/
Fijiaaron 
also check out rstakeout – monitor files
http://nubyonrails.com/articles/automation-with-rstakeout
and autotest
http://nubyonrails.com/articles/autotest-rails
scons is a build tool for python
http://www.scons.org/
Interesting article about using Rake to bulid Java projects, and the birth of a new project called Buildr
http://www.infoq.com/news/2007/05/fast-ruby-builds-with-buildr
http://blog.labnotes.org/2007/04/18/introducing-buildr-or-how-we-cured-our-maven-blues/
http://buildr.rubyforge.org/
Also Raven:
http://raven.rubyforge.org/