Ai Weiwei is missing! The provocative Chinese artist was arrested at the Beijing airport on April 3 2011 and hasn’t been seen or heard from since. My friends Amy Harwood and Ryan Pierce of Signal Fire have started a campaign for artists to show their solidarity with him and their opposition to China’s ongoing crackdown on dissent. The site is weiweiworkshere.org and features downloadable graphics for people to print out and post in studios, public spaces, galleries; wherever art appears. Do it now. You’re next.