Heads-up, locals: China's Mobile, Unicom and Telecom carriers are building a city-wide public WiFi network across Beijing. Residents will enjoy free 2Mbps internet for up to three years, if they sign up to the "My Beijing" service. Like most things that are gratis, there's a catch: you have to submit your phone number in exchange for access. Privacy enthusiasts aren't thrilled at the idea, (you know, since it's backed by t