application.rb

class Application < Merb::Controller

  before :set_lang

  def _template_location(action, type = nil, controller = controller_name)
    lang = params[:language]
    action = "#{action}.#{lang}" unless lang == 'en'
    _conditionally_append_extension(controller ? "#{controller}/#{action}" : "#{action}", type)
  end
 
  protected

  def set_lang
    lang = params[:language] || request.subdomains(Merb::Config[:domain].split('.').count-1).last
    # this should ensure we don't get anything strange
    params[:language] = %w(en th).include?(lang) ? lang : 'en'
  end

end