According to a Sept 2011 Nielsen study smartphones have grabbed 40% market share in the U.S. That means 4 in 10 Americans who own mobile devices own smartphones. The other six own feature phones for now at least. Nielsen projects that smartphones will pass feature phones in the U.S. and reach 50% market share by Christmas 2011. This is all the more amazing considering only 21% of American wireless subscribers were using a smartphone as of the fourth quarter 2009. Data such as these are sending marketers into a frenzy as they rush to engage consumers in this new and exciting channel. Check out this infographic below which illustrates the rate at which social sports fans are using smartphones.