"You guys are so fast I didn't have time to write anything about it. The purpose is to let users over a certain karma threshold flag spam and troll submissions.
It should only be used for spams and really egregious trolling, not for stuff that's merely vapid or mistaken or off-topic.
Please don't click on it just to try it out. Flags are really being recorded, so flagging something randomly could damage the reputation of the flagger and/or the submitter of the thing that got flagged."
It would have been nice to simply add a tooltip or other means of indicating some clue of what this feature was. Naturally I clicked it hoping I would be taken to a page that explained its use (since there was no help link or other info available).
I then unflagged the post since I realized it was just some sort of boolean indicator. Poor design IMO. Someone could think "flagging" was a way of marking interest or something.