"The following lists the top smartphone operating systems by market share in the United States in October, according to research firm comScore.ComScore conducts monthly user surveys. The following list is derived from a three-month average ending in October of U.S. mobile subscribers over the age of 13. ComScore asked respondents what type of phone they own, and derived operating system information based on those responses.According to comScore's numbers, around 36 million Americans own a smartphone, while around 196 million own a "non-smartphone" (or a device that does not feature an open operating system).These numbers represent current phone ownership at a specific point in time, rather than the total number of devices sold with a particular operating system.These numbers are the most recent available from comScore, and represent the market situation after the introduction of the Palm Pre and the iPhone 3GS. However, the Pre's webOS operating system is not listed because the device does not yet have a large enough installed base to accurately be counted by comScore's survey."  via fiercedeveloper.com