Or comparison, if you prefer.
A youngish friend seeking his PhD in history - I think I have referenced Josh on other occasions here - tells me that the some historians of religious history are making a point of spelling Puritanism with a small "p," to emphasise that it was a movement, not a unified whole in any way, with contradictory trends, fads, backwaters, and saints or charlatans.
I am thinking the same thing about the Emerging Church at this point. Seeing it as a single trend, even a diverse one, doesn't capture it. Spell it with a small "e." It is many things, some of them contradictory.
And that is exactly what it should be, if it is to have any permanent positive effect.