As of the latest version of Chatter Mobile(v4.2), you can now include VF tabs in the app. Mark the VF page as Available to Mobile apps and create a tab that is also marked as mobile ready. Then go to Administer>Mobile Administration; you’ll find a new option called Mobile Navigation. This lets us rearrange “stage left” in the Chatter Mobile app. We can add and remove standard components and also add our mobile enabled Visualforce tabs here.
Once you are all done, fire up Chatter Mobile!
I wrote a blog post with a bit more info: http://www.verticalcoder.com/2013/11/06/chatter-mobile-and-visualforce/