I just got a couple badges for this answer (made Community Wiki because I'm just expanding on a deleted answer, so I don't think I deserve the rep).
I'm the only person who ever touched this particular answer, so obviously in this case if there are badges to be handed out I must be the person who receives them. In general, though, a CW answer isn't going to be attributed to a single individual. So who is treated as its owner for badge purposes? The original poster? The person who contributed the most?