I have created a plugin named bing_translate_yaml that allows you to simply translate your Ruby on Rails YAML files into any language using Bing. The plugin takes your YAML files from the config/locales folder and converts them to any language of your choice.
In your Gemfile:
$ bundle install
Make sure you have your translation files in e.g.:
config/locales/en.yml (English) config/locales/de.yml (German) config/locales/es.yml (Spanish)
$ rake translate from=en to=es
This will create (or update) the following file:
Simple as cake! Enjoy :-)