The Twitter guys use SMS as an excuse for a lot of the inadequacies of Twitter. Why do we have shortened URLS? SMS's fault. Why no enclosures? SMS. Even if it doesn't make sense, it's SMS that's the reason everything sucks on Twitter.
I'm taking the guys at face value, they really mean this, but I think they got the relationship between Twitter and SMS wrong. Twitter isn't an application of SMS, it's what SMS is growing up to become -- an n-way publishing medium. It's SMS 2.0. Forget about bridging to SMS. It's already there. It's like pondering life in the universe without thinking about life on Earth, which is of course part of the universe.
Blogging was Web 2.0, really was. We said web publishing should be one to many, and many to many, even one to one. You should publish any which way you want. In that sense, what was interesting about SMS before Twitter is an order of magnitude greater in Twitter. It makes SMS type messages flow in a million ways where the old kind just went one way.