Prominent Chinese artist Ai Weiwei  has installed four live webcams at his home in Beijing as a symbolic protest against the police's 24-hour surveillance of him. [Update: The Chinese authorities ordered  Ai to turn off his webcams yesterday on April 4.]
Last year on April 3  [zh], Ai Weiwei was arrested at the Beijing airport under the pretext of being “a threat to national security”. The police action was believed to be part of the crackdown of the call for Chinese Jasmine Revolution  inspired by the Arab Spring. Ai was detained for 81 days in a secret location and interrogated more than 50 times for inciting state sedition, economic flaw, tax evasion, distribution of indecent and obscene photos, double marriage, illegal money exchange, etc.
He has been under probation since June 22, 2011. Since then he has been under constant surveillance by the police. There are at least 15 cameras outside his house.
The four webcams are placed  parallel to his computer screen and near the ceiling to oversee his working desk, courtyard and bedroom. Below is a screen capture of him sleeping on April 3:
As a part of Ai Weiwei's artivist performance to remember the anniversary of his disappearance, human rights lawyer and Ai's friend Liu Xiaoyuan interviewed Ai on Twitter:
A less sarcastic explanation of his action can be found at New York Times. Ai Weiwei said to the news agency:
In my life there is so much surveillance and monitoring – my phone, my computer. Our office has been searched. I have been searched, every day I am being followed, there are surveillance cameras in front of my house. So I was wondering why don’t I put some [cameras] in there so people can see all my activities. I can do that and I hope the other party [authorities] can also show some transparency.