Zynga, the online game company which popularized FarmVille and CityVille on Facebook has filed for a $1 Billion I.P.O. The company chose Morgan Stanley for the lead offering along with Goldman Sachs (NYSE: GS), J.P. Morgan Chase (NYSE:JPM), Bank of America Merill Lynch (NYSE: BAC), and Barclays Capital (LON:BARC).According to the New York Times, "Zynga’s filing comes among increasing sense of urgency among some of the largest Web companies to go public."However, Zynga's enthusiasm for its I.P.O. may be substantially higher. According to individuals informed on the situation, Zynga is believed to market up to 10% of their shares at a valuation around or drawing around $20 billion.The online game start up was founded four years ago by 45-year-old chief executive Mark Pincus.