Looks like Foursquare is experiencing the questionable honor of getting the attention of the Chinese government. Authorities appear to have blocked the service, at least in mainland China, according to many a tweet from Chinese location sharers.

While this obviously can’t easily be confirmed, it appears as though the block is a result of Foursquare users checking in to another kind of square: Tian’anmen Square, the infamous plaza in China’s capital of Beijing (Peking).
TechCrunch