How to alter node title link?

This is done in template_preprocess_node() in node.module on line 1451 (http://api.drupal.org/api/drupal/modules%21node%21node.module/function/template_preprocess_node/7).

function template_preprocess_node(&$variables) {
  ...
  $variables['node_url']  = url($uri['path'], $uri['options']);
  ...

You could change it to anything else in your own module in mymodule_preprocess_node() function like so:

function mymodule_preprocess_node(&$variables) {
  $variables['node_url'] = 'some/other/path';
}