If you tried to quantify and sum each of the various innovations which enable twitter, you'd find a relatively small amount of consumer led innovation in the ap

If you tried to quantify and sum each of the various innovations which enable twitter, you'd find a relatively small amount of consumer led innovation in the application layer, served by a huge amount of top-down innovation in the technology stack. And regardless of the implementation tech (IM, email, etc), I'd imagine you'd find the same thing to be the case. I don't mean to say that consumer-led innovation can never produce radically new technologies, just that the general direction of innovation is still top-down.