Google Data on Rails

"Where's Ruby on the list of client libraries?"
Motivated by the ferocious appetite of our developers and the enduring popularity of Ruby on Rails (RoR), Jeff Fisher has forged a Ruby utility library from the fiery depths of Mount Doom. Mind you, it's not a full-blown client library, but it does handle the fundamentals like authentication and basic XML manipulation. It also requires you to work directly with the Atom feed using the REXML module and XPath.

http://code.google.com/apis/gdata/articles/gdata_on_rails.html