I'm only halfway there. I really like this idea ...
... because it's common to see more than one badge on a discussion, and they tend to cover up the smaller avatars used in the index. I don't see a point in showing an avatar if it will be mostly obscured by badges. And semantically speaking, the badges belong to the discussion (represented by the title) not the user (represented by the avatar), as Kakifrucht pointed out already.
EDIT: My only concern is how we'd handled "Followed" posts. The little pushpin and lock icons are fine, but I suspect that a small yellow star isn't going to cut it. Perhaps that one should be in a yellow circle, as Franz suggested.
On the other hand, I don't really see a need for this ...
... because the avatar is larger to begin with, and it makes more sense to put the group badge on the avatar. I'm also worried that the smaller group icon next to the name will be less noticeable, as Franz indicated.
So I'd vote yes (with the "Followed" caveat) and no, respectively.