Given the number of subject-only (nm) posts, would it make sense to also be able to do this from the main board without having to go into the message? Clicking on a thumbs up/down if they're already there would be easy, not sure what you'd do for posts that don't have one yet -- maybe the option shows up when you mouse over that line?
Just a thought -- given the rapid-fire board style that is CB it would make sense to bring that functionality up to tat level.
That said, maybe you want the extra step to keep people from just going crazy with it. I don't know.