From a WSJ brief report:
[T]hey came, they saw, and they left Chinese social networking Web sites like Renren.com (formerly known as Xiaonei), Kaixin001 and 51.com to fight amongst themselves for the market.
Then, to the chagrin of both expatriate and Chinese users (the number of which appeared for a time to be growing), China’s censors blocked Facebook. Blocks of overseas Web sites such as YouTube.com are a fact of life here, barely acknowledged and never explained by the government.
Now the country has just about 14,000 active users at the beginning of October, down from a million in July.
Ahh, the power of China.