The technology in itself is emerging in the sense that it is not yet mature. I wish it was. But that isn't the point. The point is that it is part of a very interesting social shift centered around "being mobile" (sorry Mr Negroponte). MMS suffers from being seen as "Photo Messaging". This is exactly like saying that email is "Photo Messaging". Seems to me that the simple fact that this debate is taking place illustrates that it is a valid topic.
Let's face it, 802.11a or 802.11g is hardly new either. As for MoveableType et al - well that, surely, has emerged as well ?
Note that I have never corresponded with, spoken to or otherwise communicated with Clay Shirky. He's a good speaker and I'm sure he's a nice & very interesting guy. Let's not get personal here.