I just published a very simple Continuous Integration App for RubyOnRails + SVN/GIT. Maybe you should give it a try:
http://github.com/felipegiotto/Inotegration/tree/master
I took some ideas of measurement and testing tools and, after trying some CI tools and not liking anyone of them, I decided to build my own, without needing to build big XML files or any other configuration. Just the way Rails was made to be.
If you like, please send me some feedback..
Best regards,
Felipe Giotto.