According to a recent report from Nielsen, Android has eclipsed iPhone and Research In Motion (RIM) devices as the number one smartphone OS in the United States.

Google Android captured the #1 ranking among smartphone platforms for the first time in January with 31.2 % market share. RIM ranked second with 30.4 %, followed by Apple with 24.7 %.

The market share of Google’s Android accelerated from 23.5% in October 2010 to 31.2% in January 2011, enough to leapfrog RIM’s BlackBerry, which decreased from 35.8% in October 2010 to 30.4% in January 2011.

In the same period, Apple’s iOS also grew insignificantly: from 24.6% to 24.7%, while Microsoft and Palm continued losing market share, ending at 8.0% and 3.2%, respectively.

However, keep in mind that these are stats from just one group, and conflicting stats from other research and mobile organizations are likely to appear in the near future.