THE PLATFORM: China's leading microblog site, Sina Weibo, has given a digital megaphone to more than 300 million Chinese.
PROS AND CONS: Many wonder if it might drive Arab Spring-style political reforms, while others see it as a new surveillance tool for the communist government in Beijing.
CENSORSHIP: Sina employs around 1,000 people who sift through the digital morass, catching sensitive material that keyword filters miss and deleting it. Not infrequently, they delete whole accounts. The government requires Sina and other Internet companies to do this in-house, and at their own cost, under threat of fines and shutdowns if they fail.