definitely agree that the state of CI projects for Ruby/Rails is not great. I was using CruiseControl.rb on Rails 2.x with success, but getting it to play well when moving to Bundler/RVM was way more difficult than it should have been.

I always thought Integrity showed promise, but then you have this: http://builder.integrityapp.com/integrity It's Integrity watching itself, and the last build from Jun 26th has failed. That doesn't inspire confidence.

So for now, I'm sticking with Hudson. It is a bit heavier, but it's available as a package on Ubuntu, so installing and maintaining is cake. I also like that fact that its flexible to do builds for any platform/codebase, which lets me consolidate all CI into one CI app.