For documentation about Ironruby I can realy recommend http://www.amazon.com/IronRuby-Unleashed-Shay-Friedman/dp/067233078. You can get a general understanding of Ruby and it handels Ironruby specific items, e.q. how to interact with the .Net Framework.
Of course you can also go to channel9 and look for presentations about the Iron languages. Presentations were given at Mix an PDC in the past. That was before Microsoft stopped the development and handed the project over to the communnity.
Look at http://blog.jimmy.schementi.com/2010/03/mix10-ironruby-and-ironpython-part-1.html for an overview of some presentations.
Hope this helps a bit.