It’s widely known that China runs a pretty tight ship – to put it mildly – on what its citizens get to see online, especially that content which is served from outside of China. YouTube has been blocked for some time and although Wikipedia was blocked for a while, it’s gradually become more available. However today Chinese authorities have brought the the Great Wall of China on a number of services including Twitter, Flickr, Bing, Live.com, Hotmail, Blogger and a number of other sites. The picture is patchy across the country between ISPs and geography, but my sources – who all agreed to be named in this post – say the ban is blanket ban is closing.

Since many of the sites don’t actually have Chinese versions, it’s hard to know how many people will be affected by this, but for those brave and resourceful business people, entrepreneurs and social commentators with strong links to the world outside China, it’s a crushing blow.

Having traveled to China last year I have a number of contacts there now who have all now confirmed the shutdown. The move is almost certainly related to the date. The Tiananmen Square Massacre happened on June 4, and the lead-up to any date like this is usually a time when the Firewall is tightened. The API to Twitter, used by clients like TweetDeck, Twhirl and Seesmic Desktop, has also been affected.