Yahoo is not building a social network, EVP Jeff Weiner promised EconSM conference-goers yesterday. "The world doesn't need another social network," he said. What the world needs instead, Weiner explained, is a network of social exchanges over the Yahoo platform. Specifically, it needs Yahoo to combine its "25 different profile experiences" into a single user profile and for Yahoo to monitor "the social exchanges" between users and then "monetize that intention." To us, that sounds like a social network. But it's not, Weiner assures us. Good thing he's familiar with bombs.