You can give Codeship a spin and see if it works for you (I am one of the founders)
Cloud based Continuous Integration and Deployment(with special Heroku support)
The first four of your items are already implemented and work fine for a number of companies
- 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.
We are working on those features as well:
- Desktop notification (potentially through Growl)
- REST API for build statuses
- Plugin framework for running other code analysis tools and reporting results in the UI
