Ai Weiweis's Sunflower seeds is exhibiting at the Tate. Here's a short film about the production of the 100 000 000 hand painted porcelain seeds. During the cultural revolution Chairman Mao referred to himself as the Sun and the people as sunflowers with their faces turned towards him. I think it's one of those ideas that transfers it's poignancy well in this video without necessarily missing anything if a visit to the Tate isn't possible.
Ai Weiwei is China's greatest living artist.