At Texas A&M University, we use a simple CAS module for authentication in Rails applications. Note that the script assumes a modified CAS server, so you'll have to make changes if you are running a spec-following version. The documentation in the script explains this issue as well as useage.
Ruby on Rails CAS ClientA Ruby implementation of the CAS client is now available at http://rubyforge.org/projects/rubycas-client/
The library is designed to easily integrate with Rails as an ActionController filter, but may be adapted for other purposes.
Documentation and example usage is available at http://rubycas-client.rubyforge.org/
The easiest way to install the client is via ruby gems, by typing the following at a shell prompt (you will probably need root access):
gem install rubycas-client