Hitwise's LeeAnn Prescott, who presented at SES Local, has posted some of the data she showed at the conference. In this particular example, what she compared was traffic to traditional yellow pages sites vs. directory sites that incorporated user-generated content:
"[G]rowth over the past year to the yellow pages custom category has been relatively flat, while the market share of visits to the custom category containing Yahoo! Local, Yelp, Judy's Book and Insider Pages has grown by 44% when comparing August 2005 to August 2006. While standard yellow pages sites are receiving significantly more traffic in terms of volume, these newer directory services, with maps, reviews, and community features are quickly catching up."