I can see that this might be true of businesses where location is a big factor.
It's most likely less true with regard to professionals like lawyers, architects, designers, etc, where you want some local contact... but it's not like grabbing some pizza before a movie.
I also think maps and listings in relation to the center of a zip code is a problem for businesses that serve a metro area... contractors, plumbers, etc... where offices can be in a low-rent industrial location that's really not closely tied in to service areas. Even ads on maps haven't licked this particular problem.
PS - I'm responding more to question of maps as a locator for some businesses than I am to the question of Google vs Yellowpages.com as a destination site. How much do listings in Yellowpages.com affect your listings in Google, if at all?
[edited by: Robert_Charlton at 7:58 am (utc) on Feb. 21, 2007]