Facebooker2_canvas_example is a project mainly written in RUBY and JAVASCRIPT, it's free.
Example project using facebook canvas
== Facebooker2 iFrame Canvas Example
This project is an example of a Facebook iFrame Canvas application implemented in rails using the Facebooker2 library. The authentication mechanism is modelled more closely after the facebook php sdk and uses NO SESSIONS for authentication, only cookies
You can find a running version of this code at:
http://apps.facebook.com/fb-canvas-example/
==Known Issues -IE client-side javascript SDK seems to still have problems when your server is using a non-standard port (usually in development).