Also central government starts to fear nationalist anger

An online artist has neatly summerized the feelings of nationalists in China toward the United States(h/t Shanghaiist). Indeed, the dilemma might be the same as like a few years ago when Japan's diplomatic missions and restaurants were under attack.
China Digital Times gives an overview of the efforts by the central government to let patriotic fever not getting out of hand, without right away dismissing it. Quoted from the LA Times:

Chinese censors have quietly warned cyber-police and Internet businesses to delete all information related to protests against Western policies, nations or companies that have proliferated in the wake of demonstrations surrounding the global Olympic torch relay and high-level calls to boycott the opening ceremony of the Summer Games in Beijing.

The notice issued this week by China’s “Internet Inspection Sector” instructs recipients to reset the keywords used to block access to certain websites, relay the instructions through all Internet distribution channels and delete the notice in a timely manner.