Much has been made of the marvelous power of 'The Great Firewall of China' — the surveillance-and-censorship system put in place by Beijing's authorities on the internet. For instance, search for any of three forbidden 'T's — Tibet, Taiwan, or Tiananmen Square — in China's major search portals, such as Baidu or Google.cn, and you'll find nothing but sweetness and roses, and nary a mention of, say, the Dalai Lama, Taiwanese independence, or a massacre of student protesters.

A search for "Tiananmen Square" on Baidu turns up a bunch of happy snaps, while the Chinese version of don't-be-evil Google merely shrugs its shoulders as if to say, "Nothing to see here".

But someone slipped up.

China internet giant Tencent — owner of the ubiquitous QQ instant messaging service — recently launched a search portal called SoSo. Curiously enough, an image search for "Tiananmen Square" (in English) turns up a picture that surely won't be there for long. Check out the first result in the search page below.

It seems SoSo has inadvertently called up a fourth forbidden T: Tank Man.

The original photo, by Jeff Widener of the Associated Press, is reproduced below.