According to the latest research from Nielsen, the high-profile launch of Apple’s iPhone 4S in the Fall had an enormous impact on the proportion of smartphone owners who chose an Apple iPhone.

NM Incite found that the iPhone has been the most frequently mentioned smartphone OS in terms of online buzz on blogs, message boards/groups, Twitter and Facebook, and online news posts, capturing 40 percent of online buzz about smartphones from July through December 2011.

In the U.S., 71% of those with smartphones own either an Android device or an iPhone. But when it comes to smartphone apps, iPhones and Android smartphones are even more dominant: 83 percent of app downloaders, that is, those who downloaded an app in the past 30 days, use iPhone or Android smartphones.

Nielsen’s third quarter survey of mobile users reveals that while only 43 percent of all US mobile phone subscribers own a smartphone, 62 percent of mobile adults aged 25-34 report owning smartphones. And among those 18-24 and 35-44 years old the smartphone penetration rate is hovering near 54 percent.

According to an August survey, 43 percent of all smartphone owners have an Android device. But if you ask only those who got a new smartphone in the past three months what kind of phone they chose, more than half (56%) will tell you they picked an Android device.

Forty percent of mobile consumers 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.

According to Nielsen, Google’s Android operating system (OS) now claims the largest share of the U.S. consumer smartphone market with 39%. Apple’s iOS is in second place with 28%.

According to Nielsen’s monthly analysis, smartphone owners, especially those with iPhones and Android devices, are consuming more data than ever before on a per-user basis.

Smartphones and the consumption of mobile data continue to grow in popularity in the U.S. – 37 percent of mobile consumers now have one – and smartphones with Google’s Android operating system (OS) are proving to be the most popular flavor.

According to Nielsen’s latest survey of mobile app downloaders, that is, consumers who have downloaded an app in the past 30 days, if you want to understand the consumer landscape for mobile apps, you have to understand the Apple iOS and Google Android ecosystems.