According to July 2011 data from Nielsen survey, 40 percent of mobile consumers over 18 in the U.S. now have smartphones.
Android is the most popular operating system, with 40 percent of mobile consumers reporting they have a smartphone with an Android OS.
Apple's iOS is in second place, with 28 percent.
"Among those who say they are likely to get a new smartphone in the next year, approximately one third say they want their next smartphone to be an iPhone and one third say they want an Android device," Nielsen reports.
However, Android leads as the "Next Desired Operating System" - 40 percent for Android compared to 32 percent for iOS.
According to July 2011 data from Nielsen survey, "these "undecideds" will be the ones device makers will be hoping to win over". Interestingly, the Late Adopters among likely smartphone upgraders are the ones most likely to be undecided about their next phone platform.