Google Data on Rails - Google Data APIs - Google Code
http://code.google.com/apis/gdata/articles/gdata_on_rails.html

This article is intended for developers interested in accessing the Google Data APIs using Ruby, specifically Ruby on Rails. It assumes the reader has some familiarity with the Ruby programming language and the Rails web-development framework. I focus on the Documents List API for most of the samples, but the same concepts can be applied to any of the Data APIs.