Marco Arment makes it pretty clear that his upcoming podcast app, Overcast, will be free with in-app purchase:
I’m sure of one thing, though: the market for paid-up-front apps appealing to mass consumers is gone. If you have paid apps in the store, you’ve probably seen the writing on the wall for a while.
Yes, free apps with in-app purchase will make more money. That doesn’t mean it isn’t a scummy business technique. So long as you sleep soundly, I guess.