You couldn’t pay me to run CruiseControl.rb now. Oh wait. You probably could.
Anyway, now that Team City has a ‘Rake Runner’, you can build your Ruby projects with Rake. It understands Test::Unit and Rspec test output as well. The runner gives you test timings, both for that build and a graph of timings in recent builds. It also gives you Rcov support as well. You can have a look on their public demo server.
It’s available as an EAP.