I've been searching around for a Continuous Integration solution for Ruby on Rails, but haven't been too pleased with the results. I came from a .NET shop that used CruiseControl.NET and was really spoiled with its ease of use and rich status/reporting.
Ideally I'm looking for:
The obvious Git/SVN and Test::Unit integration
Integration with Rake and/or Capistrano
A web interface showing the status of the build
Email notification of failed builds.
Desktop notification (potentially through Growl)
REST API for build statuses
Plugin framework for running other code analysis tools and reporting results in the UI