Ruby on Rails 3.1 and 3.2 Development with Cloud Foundry

http://docs.cloudfoundry.com/frameworks/ruby/rails-3-1.html

A Mongo ORM for Ruby

http://mongomapper.com/

Ruby Development with the MongoDB Service

http://docs.cloudfoundry.com/services/mongodb/ruby-mongodb.html

Installation in Rails 3

http://mongomapper.com/documentation/getting-started/rails.html

MongoDB Data Modeling and Rails

http://www.mongodb.org/display/DOCS/MongoDB+Data+Modeling+and+Rails