Change Page Title on Add Node Page
There are a few different ways you could do this, but the way you asked for would utilize hook_form_alter():

&lt;?php
function custom_form_alter(&amp;$form, &amp;$form_state, $form_id) {
  if ($form_id == 'mynodetype_node_form') {
    drupal_set_title('My new title');
  }
}
?&gt;


This would be in a custom module named custom.module... drupal_set_title(), when called anywhere in the page load, will set the title appropriately. You're basically hooking into the node form rendering process, and saying 'set the title to what I want' at that point.

If you'd like to further differentiate what the title would be depending on whether the user's creating a new node or editing an existing node, use Devel module's dpm() function to print out the $form_state array, and check to see if there's a node ID already or not—if there is, you are editing a node; if not, you're creating a new node. Set the title appropriately.

While hook_form_alter() would probably be the most robust page (in case someone was viewing the node add form from somewhere other than node/add/[type]), you could also check the path in hook_init() and set the title there, or from a variety of other places (in Drupal 7, hook_page_alter() perhaps).