+6  A: 

Try this CruiseControl.rb

http://cruisecontrolrb.thoughtworks.com/

CruiseControl.rb is written in Ruby and designed for ruby.

Another one is Hudson, it is built in Java, but it has a plugin for ruby

https://hudson.dev.java.net/

Josh Moore
+2  A: 

Give Cinabox a try (I'm the author). It is intended to make this as simple as possible, and uses cruisecontrol.rb. There is a screencast and readme. If you have problems, open a ticket using the LightHouse link in the readme.

Good Luck!

thewoolleyman
+2  A: 

There is a lightweight CI server written in Sinatra called Integrity which you might want to take a look at. I mainly used it because it supports git.

http://github.com/atmos/integrity/tree/master

MatthewFord