Route / to /users/login.

config/routes.rb

@@ -12,6 +12,7 @@ ActionController::Routing::Routes.draw do |map|
   # You can have the root of your site routed by hooking up '' 
   # -- just remember to delete public/index.html.
   # map.connect '', :controller => "welcome"
+  map.connect '', :controller => "users", :action => "login"
 
   # Allow downloading Web Service WSDL as a file with an extension
   # instead of a file named 'wsdl'