I'm not seeing the 'What are you doing?' line, so all I can do is post to my wall. Is there another way to update your status?
(Note: I'm not Facebook savvy at all, and it might be that I'm just doing something wrong. if I am, that'd be good to know, too.)::
Just type it in that big white box on the top of your page. The one that says "What's on your mind?" That white box is now multi functional, and used for status updates/wall post/photo uploads/most facebook functions.