Nielsen released its November 2010 smartphone market share data for the U.S. on Monday, and highlighted two main observations along with its report. First, Apple’s iOS platform held on to the lead it won in October, when it passed RIM to become the most popular OS in the United States with 27.9% of the market. RIM’s BlackBerry OS fell to the No. 2 spot at that time with 27.4% and Android closed in on both platforms with 22.7%. Nielsen’s new November data shows Apple climbing slightly to 28.6% while BlackBerry OS just barely holds its position above Android, falling to 26.1% compared to Android’s 25.8%. Nielsen’s other observation emphasizes Android’s huge popularity over the past six months. Among those who made smartphone purchases in the last six months in the U.S., 40.8% bought Android devices, 26.9% bought iPhones and only 19.2% purchased BlackBerrys.