A new Rails Kit is now available: The Helpdesk Rails Kit makes it easy for you to add a support center to your existing Rails app, or even to just run a standalone support site along-side your existing Rails app.
You get an admin interface for you and other people on your team to see, route, and handle tickets from your customers and update your knowledgebase, and your customers get a web interface to keep track of their tickets and view your support articles. The Helpdesk Kit also provides email integration, so you can have your customers send email to your existing support email address and get responses back from that email address, while you and your team can still view, tag, and assign the tickets that come in via email using the web interface (which also has an ATOM feed, to keep you on top of everything).
If you've been wanting a support site for your Rails app, check out the Helpdesk Rails Kit. And, If you need some recurring billing for your Rails app, don't forget about the Software as a Service Rails Kit. With these two Kits, it's almost SaaS-in-a-box. :)