Data vs API

Brady Forrest nearly equates Zillow's free (as in speech) neighborhood boundary data with Urban Mapping's free (as in beer, while supplies last, domestic only -- hey, no sharing) neighborhood ID API. I'm not calling on anybody to give away their proprietary data, just pointing out that, in fact, these things are only equivalent if you have no other application than answering simple questions like: "what neighborhoods contain (long, lat)?" There are many interesting questions that you can only ask with the boundary data itself, or only by hammering the Urban Mapping services Monte Carlo style.