Someone

SELECT DISTINCT ON (post.id) * 
     FROM list_posts AS post
     LEFT OUTER JOIN private ON (post.id = private.pid)
     LEFT OUTER JOIN configuration AS config ON (config.key = 'official_user')
     LEFT OUTER JOIN count_comments AS ccount ON (post.id = ccount.pid)
        WHERE
           post.private = false            --Post is not private
           OR private.uid = 1              --User is allowed to view post
           OR config.value = 1 --User is the official_user           
     ORDER BY post.id desc