I already run reports with that data, just under different labels.
Many of our stores no longer pay for what you call "white page" - if the search is specific enough Google already gives us the real estate and if not we rank exceptionally well organically in this area.
Almost all the reports I run exclude all "white page" results in order to ensure my organic results are real.
All our substantial increases are on geographical or industry terms that they previously didn't rank well for.
Believe me when I say I don't make assumptions based on Analytics - I've been studying Google Analytics reports and working with their tools and dashboard for over 6 years now on a weekly, if not daily basis. My combination of Webmaster Tools, Analytics, Chartbeat, In-house Analytics and AdWords Analytics provides very good data sets that show not only how users get to the site, but which sources result in the best clickpaths, which sources yield the highest number of goals, which organic keywords lead to the contact page most often, which organic keywords land users on inventory pages vs. the homepage and many other key data sets. We build off of what works for each site and continue to make improvements that are specific to that website's own key performance indicators.
Long story short - "Yellow Pages" has been my grind for the past 4 years and will always be my primary focus.
We've found numerous ways to work in this area that have been far more effective than I ever expected, but we also see significant growth on the "White Pages" side that has a very strong correlation, even when removing returning visitors.