Just a quick list of natural language processing resources for Ruby:
* MIT has a list of [AI-related Ruby extensions](http://web.media.mit.edu/~dustin/papers/ai_ruby_plugins/).
* Jason Adams, who does “opinion mining for a startup in Atlanta”, has a list of [NLP Resources for Ruby](http://mendicantbug.com/2009/09/13/nlp-resources-for-ruby/).
* Nick Sieger has a post on [RubyConf: Natural language generation and processing in Ruby](http://blog.nicksieger.com/articles/2006/10/22/rubyconf-natural-language-generation-and-processing-in-ruby).
* Finally, there are a couple of papers that mention Ruby and NLP: [“Trust Region Newton Method for Large-Scale Logistic Regression”](http://ntucsu.csie.ntu.edu.tw/~cjlin/papers/logistic.pdf) and [“Natural language question answering: the view from here”](http://www.loria.fr/~gardent/applicationsTAL/papers/jnle-qa.pdf).