According to the latest data from research firm ComScore, the iPhone has overtaken Windows Mobile in U.S. smartphone market share for the first time. ComScore conducts monthly surveys of U.S. mobile subscribers over the age of 13, asking them what type of phone they use, and then derives OS market share from those numbers. Based on a three-month average ending in October, the iPhone has over 8.9 million users, compared to Microsoft’s Windows…