It's the data, dumba--

Nicholas Carr reviews the new real estate data mashup site, Zillow.com -- and hits paydirt with this point:

Entrepreneurs are launching all sorts of sites and services that are built on data that they're siphoning out of third-party sites and databases. Sometimes, the secondhand data is good; sometimes, it's not. The process of chopping up and bundling data from many different sources can, moreover, amplify inaccuracies. Combine bad data from two different sources and you may get bad data squared. Unfortunately, to the user, the inaccuracies are invisible. The slickness of the interfaces of sites like Zillow, with their tables and graphs and calculators, gives the appearance of credibility, even if it's not warranted. To use the memorable phrase coined by comedian Stephen Colbert, Web 2.0 sites can all too easily supply "truthiness" rather than truth.