Today is Yelp Day in San Francisco, by order of Mayor Gavin Newsom. If memory serves me correctly, this is the second annual Yelp Day. It’s a nice PR boost for Yelp. For the city, it’s probably a way to give a nod to a local tech company while also encouraging people to go out and spend some money locally on a nice dinner (write a review while you’re at it). Yelp has made a huge splash in San Francisco, which has been a big driver of the online review phenomenon (latest data) we’re seeing nationally — or is it the other way around?