Stephanie linked to a post today where Guillermo wrote a rough importer for WordPress back in 2009 that imports a Delicious XML export into your WordPress install as Posts. It needed some reformatting of the functions to register properly with WordPress & not cause errors.
Download the Delicious Importer here.
How do you get your Delicious bookmarks as an XML file?
Use this URL: https://api.del.icio.us/v1/posts/all but place your username / password inbetween the :// and the rest of the URL with an @ before the URL. Example:
https://my_username:my_password@api.del.icio.us/v1/posts/all
Once you have the exported XML file, install and activate the Delicious Importer plugin and import the XML file as you would a WordPress XML file.
Important – all your bookmarks will be imported, private ones, too. If you don’t want it imported, you will need to edit the XML file beforehand.
Update: Stephanie’s got a version on her site & hers handles private tags as private posts or invisible links. Grab a copy of it here.