Shame on you for slipping an ad for Microsoft in with the "Freshly Pressed" topics on the WordPress.com home page (but thank you for identifying it as an advertisement).
Since you're getting paid to show off IE9, I can't trust that the latest news article, "IE9 User? You’ll Love ‘Pinning’ Your Blog" is actually a genuine viewpoint of the WordPress staff -- so I'm not going to bother to read the post.