Not real sure what they are called in this forum software package, however, in other software packages I've seen them called Topic Ranking/Rating icons. A way of saying that this is a really good topic for example.
This is the first time that I've seen them on any of the forums. Maybe Shad accidentally enabled them as he's making changes trying to correct and/or add new features. We'll just have to wait for an answer from Shad to know for sure.