I have built a custom post type called article and the information given on the admin summary screen is sparse. I was able to add the featured image post thumbnail image using the http://codex.wordpress.org/Plugin_API/Action_Reference/manage_posts_custom_column from a tutorial.
However I would like to be able to get an overview of the categories and sub categories that these posts have had assigned to them on the admin page. ie adding a column for that part?
Here is the code that I have used to register the taxonomy in the custom post types code
The register_taxonomy function has a parameter called show_admin_column
that will handle adding a column. Have you tried that?
eg:
register_taxonomy(
'my_tax,
'post_type',
array(
'label' => 'My Taxonomy',
'show_admin_column' => true,
)
);