These demographic data are freely available but not many people are mapping it in this way beyond a few B2B vendors. So beyond the novelty factor, why is this important?
Local targeting becomes demographic targeting (and more) when you start layering more information (e.g., HH income) on top of maps. Imagine Google, Yahoo! or MSFT offering this capability via their advertising platforms. You select areas and can target by income, age, renters, homeowners, ethnicity, etc. And there’s lots more data out there that could be further layered on top of maps, taking ad targeting to incredibly precise new levels, all based on location.
Now you can start to see how maps + demographic data makes local search incredibly powerful. I would imagine that we’ll start to see such offerings in the not-too-distant future.