You can post on your WordPress.com blog from within the Facebook site. I love it when technology conspires to let me do more things from one place.
The app could be better. For instance, I can’t control how many comments and/or posts display on my profile. Seems like a no-brainer there. What would also be nice is having the rich text editor like the WordPress.com GUI in Facebook. I can do HTML easily, but it’s nice to have tools that let me think about the post more than the code.
Twitter! Flickr! YouTube! Get on the ball, here! Let me post from Facebook!