I think the chatter wall is for conversation that takes place on your page and for you to initiate conversation on other pages. It does not look like this can be broadcast out to everyone in the group. I hope they change it because I have seen some interesting "chatter" and it would be nice to feature it.
Blog posts can be featured and of course if you start a forum discussion, it is featured.
Thanks Jason. I think I can talk to myself without typing it out :) so in future I'll probably use the forum if I think I have something to share, like a very interesting article I've just read IT recruiting.