We have discussed this internally several times for a long time, I think the last agreement we reached was that 3D should be treated similarly to news, meaning they should be posted in the main forum of the discussion. For example, if you are talking about Blu-ray 3D movies, it should be posted in the Blu-ray Movies forum, 3D HDTV goes under Display Discussion, 3D receivers in the Receiver forum etc.
Personally I've been pro a separate forum for 3D, at least as long as it's a new technology (which it will be for a while) and people might want to discuss the "complete experience", which would be a valid reason for a dedicated forum. I can bring it up again
