They show above the tags, look here. and no it isn't a modification, comes straight from vBulletin it'self.
The acorns above the ranks is the reputation. When I go to vBulletin Options - User reputations, and enable it. it appeared. however, when I disable it, it disables it for the posts, and the profiles.
This fansite I know only has it on posts, that's what I'm trying to figure out.