Yes, this is an update, and it will be some cool stuff I'm certain.
But as far as I know it doesn't even go into the game installers directly, it's a separate download just as before with the other map pack, so I don't even see how this is "official". I do find this rather silly actually, but whatever floats peoples boat I spose.
How this addon will work will be interesting, but I myself wouldn't call this a "proper" update yet.