Moondog is correct, you are conflating the 48 hour waiver with transit. The OP was transit:
"1. Visas are not required of aliens who hold air tickets to the final destination and have booked seats on international airliners flying directly through China, and will stay in a transit city for less than 24 hours without leaving the airport.
2. Visas are not required of passport holders of the following countries, who transit through Pudong Airport or Hongqiao Airport of Shanghai, provided they hold valid passports, visas for the onward countries, final destination tickets and have booked seats,
and stay in Shanghai for less than 48 hours : Republic of Korea, United States, Canada, Australia, New Zealand, Germany, France, Netherlands, Belgium, Luxemburg, Portugal, Spain, Italy, Austria, Greece, Sweden, Denmark, Norway, Finland, Iceland."
This is copied directly from the Chinese embassy (last updated 9/2008)
http://www.china-embassy.org/eng/hzqz/zgqz/t84242.htm
The Chinese have not updated that leaving the airport is now allowed in PEK (see my bold) but the tansit rules are not limited by country.