On October 29 and 30, 2006, fourth Auto-ID Labs CJK workshop was held at Fudan University in Shanghai, China. The Auto-ID Labs CJK workshop is a workshop jointly organized by three Auto-ID Labs located in East Asia (CJK is an abbreviation of China, Japan, and Korea). It started last year aiming at sharing of studies of each lab and promoting the collaboration among labs. So far, the workshop has been held in China (November 2006), in Japan (March 2007), and in Korea (July 2006). Every time, about forty researchers join the workshop and have presentation sessions about their studies. In this fourth workshop, we had 21 presentations in five presentation sessions in three research streams: business model/application, software/network, and hardware. Also panel discussion sessions were held as a new activity to further promote the collaboration among labs. CJK Auto-ID Labs are expecting to announce new projects started from this workshop.