gistfile1.rb

Article.all(
  :select => "articles.id, articles.title, slugs.name",
  :joins => "INNER JOIN slugs
              ON  slugs.sluggable_type = 'Article' AND
                  slugs.sluggable_id = articles.id AND
                  slugs.id = (SELECT id 
                              FROM slugs
                              WHERE slugs.sluggable_type = 'Article' AND
                                    slugs.sluggable_id = articles.id
                              ORDER BY slugs.created_at DESC
                              LIMIT 1)")

oh yeah, subselects