I've noticed in the past couple days that my Facebook app (1.6.0.21) has been running a little differently than in the past. Now when I get a notification that somebody has made a comment on a status, wall post, picture, etc, I still get the notification but do not have the opportunity to comment back, rather I have a link to the mobile site to view the comment thread. It isn't the end of the world, but I liked the old way more.