File this under "Another China supassing the U.S. statistic"…
It's possible that in the next two years, China may overtake the U.S. as the world’s largest economy (depending on how you analyze the two countries' respective positions).
The U.S. has a nearly $15 trillion annual output, which dwarfs China's $5.0 trillion economy.
However, according to The Conference Board, if one considers purchasing-power parity (PPP), (which takes into account the goods and services a country’s currency actually buys at home), the trend of China's real purchasing power measured against a slowing U.S. economy suggests that China could have a larger economy than the U.S. by 2012.