I have had a look on how the posts from this blog are listed on Technorati and most if not all of the titles are coming through as "Permalink". I was going to try WordPress.com support but they are off for the weekend. A trip to the WordPress.com forums was then in order and a few helpful folk put me right on this one: apparently Technorati uses the permalink titles when extracting post summaries from WordPress.com blogs and in the Andreas04 theme that I am using, these are all hard-coded as "Permalink". I have left the theme’s author in on this and going to try WordPress.com feedback tomorrow. In technical terms and from what I can see, the fix needed is as follows: change title="Permalink" to title="Permanent Link: <?php the_title(); ?>" in the single.php, page.php and index.php files in the theme.