pages_controller.rb

class PagesController < ApplicationController
  verify :params => :name, :only => :show, :redirect_to => :root_path
  before_filter :set_locale, :ensure_valid, :only => :show

  def show
    render :template => "pages/#{current_page}"
  end

  protected

  def current_page
    @page ||= params[:name].to_s.downcase
  end

  def set_locale
    I18n.locale = params[:locale]
  end

  def ensure_valid
    unless template_exists? "pages/#{current_page}"
      redirect_to root_path
    end
  end
end

routes.rb

ActionController::Routing::Routes.draw do |map|
  map.page '/:locale/:name', :controller => 'pages', 
    :action => 'show', :requirements => { :locale => /es|en/ }

  map.root_locale '/:locale', :controller => 'pages', :action => 'show',
    :name => 'index', :requirements => { :locale => /es|en/ }
  map.root :controller => 'pages', :action => 'show', 
    :name => 'index', :locale => 'es'

  map.connect ':controller/:action/:id'
  map.connect ':controller/:action/:id.:format'
end