Custom Post Types and Categories?

It appears that although register_post_type() will add the new post_type immediately, it seems as though you need to bind up the logic into a function, and add it to the init action for the categories taxonomy to be associated with the post_type. A working example follows:

function add_articles_post_type() {
  register_post_type("article", array(
    'label' => 'Article',
    'public' => true,
    'hierarchical' => true,
    'supports' => array('title','editor','author','thumbnail','revisions')
  ));
  register_taxonomy_for_object_type('category', 'article');
}
add_action('init', 'add_articles_post_type');