User blog comment:BertH/New Forums now available in Labs/@comment-413936-20121220045116/@comment-5275700-20121220193747

Are you referring to the Topics function at the bottom of every thread? If so, any user can edit the topics and remove or add topics as needed. But it sounds like you might mean moving a thread from one board to another, which is also possible. That option is on the "More" drop-down menu.