Effective on January 1st, 2013, both Beijing and Shanghai will allow transit passengers from 45 countries to stay in these cities for up to 72 hours without a visa.
Shanghai has already been offering visa-free transit stays for some certain passport-holders for a maximum of 48 hours. In Shanghai, transit passengers holding third country visas and plane tickets can enter Shanghai through the city’s two airports, Hongqiao (SHA) and Pudong (PVG); in Beijing, transit passengers can enter only through Beijing Capital International Airport (PEK).
The 45 visa-free countries are:
Argentina, Austria, Australia, Belgium, Brazil, Brunei, Bulgaria, Canada, Chile, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Japan, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Mexico, Netherlands, New Zealand, Poland, Portugal, Qatar, Republic of Korea, Romania, -Russia, Singapore, Slovakia, Slovenia, Spain; Sweden, Switzerland, United Arab Emirates, Ukraine, United Kingdom and United States.
Update:
Starting in August, Guangzhou will also allow visitors traveling to 3rd country to stay in the province up to 3 days visa-free.