Twitter was never popular in China, and it has very strong competitors ready to fight it back. The most important one is Sina Weibo (新浪微博). Sina Weibo is more or less the same size as Twitter with +200 million accounts. But it offers much more than Twitter. It has an applications platform, successful internal currency (Weibi), live chat that is a clue for most Chinese users, and kind of dashboard sporting the most interesting content added to the website. Sina Weibo is connected to another service, called Weilingdi, which is basically what we know as Foursquare.
Sina Weibo can exist in Chinese political environment because of legion of moderators, that are constantly filtering content to be compliant with government instructions. Twitter is not prepared to do the same, and its western users would tweet a lot about censorship if somebody dares to impose it on this website. This is why regardless of the Chinese interface, it will stay blocked in mainland China, as it is blocked since 2009.
Of course, there are Chinese speaking people outside of mainland. They can use Twitter. But they could do that also with the English interface. And most probably they would choose Sina Weibo anyway, they already have their friends and families there.
