Add a lang param in routes

(Shameless self-promotion) You can also use my translate_routes plugin:

  http://github.com/raul/translate_routes/

which not only adds a locale parameter and prefix:

http://localhost:3000/en/articles/1/comments/1
http://localhost:3000/es/articulos/1/comentarios/1

But also allows you to translate the static fragments of your routes,
improving your SEO performance. Your current xxxxx_path and xxxxx_url
helpers will be transparently converted to the current request's
locale, so you just need to add a .yml translations file and one line
to your config/routes.rb.

Hope it helps!