officially.
http://news.yahoo.com/s/ap/20110214/ap_on_bi_ge/as_japan_economy
Japan confirms China surpassed its economy in 2010
By TOMOKO A. HOSAKA, Associated Press Tomoko A. Hosaka, Associated Press – 1 hr 29 mins ago
TOKYO – Japan confirmed Monday that China’s economy surpassed its own as the world’s second largest in 2010 and said a late-year downturn was Japan’s first quarterly contraction in more than a year.
Japan’s real GDP expanded 3.9 percent in the calendar year in the first annual growth in three years, but it wasn’t enough to hold off a surging China. Japan’s nominal GDP last year came to $5.4742 trillion, less than China’s total of $5.8786 trillion, the Cabinet Office said.