User blog comment:Toughpigs/Wikia's new Forum demo/@comment-5395580-20120726115055/@comment-10370-20120726204739

We're using "thread" as the same namespace for Forum and Message Wall because we're going to build a feature that lets people move a thread that's posted in the wrong place.

That happens all the time on wikis, especially with new people -- someone starts a conversation on a user talk page that should be on article talk, or in the forum. The experienced users end up removing the post from the wrong place, and then pasting it to the right place -- but the newbie doesn't necessarily know where their question went.

Using a consistent Thread namespace, we can have a feature that moves a thread from one board to another, or from a Message Wall to a forum board, and still keep all the links and notifications intact. Newbie gets a response, follows their notification to the correct place, and now they know where to post that kind of question. That'll be coming up sometime later this summer.