If you work in a project with i18n maybe you found useful this small trick for forcing the locale in a block:

 module I18n 
   class << self  
     def in_locale(new_locale, &block)
       old_locale = I18n.locale
       I18n.locale = new_locale
       yield
       I18n.locale = old_locale
     end
   end
 end

This is very useful, for example, when you have to send a notification to a user in his locale, not in the current locale, so you have to do it in this way:

   I18n.in_locale(@user) { UserMailer.deliver_new_comment(...) }

Hope it helps.