Beijing Wicity is setting out to cover several key parts of Beijing with Wi-Fi access, and it is supposed to be free until after the Olympics, which will take place August 8-28, but service is spotty in advertised coverage areas.
Danwei reports that Wicity, not to be confused with WiiCity (which doesn't exist, but would be a pretty fun place), is a project of Chinacomm (中电华通). Wednesday is the first day of the test stage.
People in an office in Beijing's Central Business District, or CBD, report that they see the network but cannot get online. I'm sitting in a cafe in Sanlitun, and I don't see the network on either my MacBook or my HTC Touch.