User blog comment:BertH/New Forums now available in Labs/@comment-3474542-20121204074520/@comment-452-20121204153244

I believe this is probably by design: the new forum link is automatically added to the on the wiki tab - so if there is a forum-url link in another menu, there would be two links to the same page. I think they've probably left it up to local wikis admins to decide what to do with the old link.