It is imperfect, but I finally found someone who figured out how to get TextMate to talk to Drupal using the Blog API. In short, the blog setup needs to include the content type you are using for blog posts after a pound sign, such as:

Blog Name http://user@www.website.com/xmlrpc.php#blogpost

Unfortunately, it doesn’t support taxonomies at all, so it’s unlikely that I’ll bother using it until I feel like putting more work into it.