Burnham’s Beat: Google Base Vertical Search RSS = Death of Walled Gardens: “In such a close-knit world the foundation of paid listings sites is starting to look more than a little shaky. About the only thing that is still missing is the ability to relate listings within a taxonomy or consistent hierarchy. However that barrier is also rapidly eroding. The first visible signs of such erosion came when a set of �vertical� search start-ups put 2 and 2 together and realized that thanks to self-publishing and pervasive search, they could create highly focused �vertical� search engines that trolled self-published Internet sites for specific information and then republished this information as one aggregated site.”