How to redirect URL of kind node/nid to its url alias I want to replicate the effect seen in http://www.drupal.org/node/1 , where you are redirected to drupal.org/about.

I have a fresh Drupal 7 installation, I create a node with a path, and don't get the effect. I have tried with module Path Auto, and nothing.
Even though you've figured out a great solution, Rules may well be a module that can help you out with this for other problems you have in the future. Rules contains several options to fire off several events. For example, if you tell Rules to React on event Content is viewed, you can then set certain events, conditions, and actions. One of these Events will cause the user to be redirected to another page - not as simple as Global Redirect, but if there's something you need done before redirecting, this could do a lot for you.