Ever since we introduced the new player to display presentations (and documents) that were in portrait mode (taller than they were wide) people have asked us to enable that for embeds on WordPress.com.
We’ve been working with the folks at Automattic over the last couple of weeks to ensure the new player works there too. So now you can just copy the WordPress.com shortcode from a presentation page and paste it into your post. Once you save and publish, that will automatically (see what I did there?) be replaced by the correct player displaying your presentation or document from SlideShare.
Geeky stuff for plugin authors: The only change we’ve made is adding an extra “&type=d” to the end of the shortcode. When you see this, you should use the new ssplayerd.swf instead of the regular presentation player.