His Sunflower Seed installation at the Tate Modern in London last year captivated and astonished. Read Adrian Searle's essay on the show in the Guardian (Oct, 2010).
Numerous international media articles, like this one from Aljazeera, report that the artist was detained by Chinese authorities on Sunday, April 3rd at the Beijing International Airport as he was boarding a flight to Hong Kong. Later, his studio was raided by police. He has not been seen or heard from since.
Call the Chinese Embassy in D.C. and demand that Ai Weiwei be released from detention - (202) 495-2266