This week, Yelp announced the inclusion of mobile activity tracking to its weekly summary for small businesses that use Yelp's free business tools The new addition came after Yelp disclosed some interesting statistics a few weeks ago about Yelp use, which revealed that over 1 in 4 searches on Yelp are performed from Yelp's iPhone application, and every five seconds, someone uses the Yelp app to call a local business. Pretty interesting, considering these stats were generated just from Yelp's iPhone app, and Yelp also has applications for 4 other smart phones.