BEIJING – China’s version of Twitter was raucous Thursday with horn-tooting over Beijing’s gold rush at the London Olympics, a digital reflection of the nation’s exuberant mood – embellished with flashing emoticons. Earlier passions have been ignited on the site by a deadly high-speed rail crash and outrage over factory pollution.

Launched in 2009, China’s leading microblog site, Sina Weibo, has given a digital megaphone to more than 300 million Chinese, prompting many to wonder if it might drive Arab Spring-style political change and democratic reforms. Others see the platform as a brilliant new surveillance tool for the communist government in Beijing.

“You get to know what people are saying and … it’s a way for the middle class to let off steam,” said Michael Clendenin, managing director of RedTech Advisors, a tech research company in Shanghai. “It’s better to let them blow off steam in a way you can control and delete rather than have 500,000 students all of the sudden show up at your doorstep.”

And Weibo is heavily censored. 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.

Though modeled on Twitter, Sina’s version has more bells and whistles, like embedded video and images for posts and threaded comments.“It’s taken a little bit of Twitter, of Groupon, of Hulu, or YouTube and essentially grafted all these pieces together,” Clendenin said. “In aggregate it’s actually much better than what Twitter is.”