From the Netherlands Environmental Assessment Agency
China’s 2006 CO2 emissions surpassed those of the USA by 8%. This includes CO2 emissions from industrial processes (cement production). With this, China tops the list of CO2 emitting countries for the first time. In 2005, CO2 emissions from China were still 2% below those of the USA. These figures are based on a preliminary estimate by the Netherlands Environmental Assessment Agency (MNP), using recently published BP (British Petroleum) energy data and cement production data.
From The Guardian: China overtakes US as world's biggest CO2 emitter
From the BBC: China building more power plants