I actually read TFA! "Churn" is apparently when people switch from one carrier to another, presumably at the end of the contract. (This answers both the parent poster, and one in this same thread)
That being said, it looks like they'd be using this data to identify who's likely to switch over, and sweeten their deals a bit to keep them - at least, in the context of cell phone companies and the like. Obviously, this has other implications outside of cell companies, but I'm sticking with the original thought on this one.
So how do we game this system? Find people who have recently changed carriers and start having them call you. Free better phone for staying with a carrier you'd probably have already stayed with!
Silly, yes, I know. Thanks.