Tiangong 1 is a "target vehicle" of China, which is planned to be launched after Shenzhou 7 and before Shenzhou 8. According to China National Space Administration (CNSA), it will be an eight ton "space laboratory module", and it is planned that Shenzhou 8, Shenzhou 9 and Shenzhou 10 will dock with Tiangong 1 in two years (which is also its lifespan in design) after the launching of the latter to form China’s first space station.
Source: The Beijing News, September 30, 2008
http://www.thebeijingnews.com/news/guonei/2008/09-30/008@015548.htm