Break up taxonomy on node form

I want to theme a node form for a blog. I've got two vocab开发者_开发知识库ularies for the blog type, one with categories and one with tags. I'd like to display the category choices in one place and the tags input in another place. Is it possible to break up the taxonomy field like that? I've tried with <?php print drupal_render($form['taxonomy'][11]); ?> but I get nothing. The IDs of the two vocabularies are 10 and 11.

This will probably get you where you need to be http://api.drupal.org/api/function/taxonomy_node_get_terms/6