According to the latest research from Nielsen, the launch of Apple's iPhone 4S last Fall had an enormous impact on the proportion of smartphone owners who chose an Apple iPhone.

Among recent acquirers, meaning those who said they got a new device within the past three months, 44.5 percent of those surveyed in December said they chose an iPhone, compared to just 25.1 percent in October. Furthermore, 57 percent of new iPhone owners surveyed in December said they got an iPhone 4S.

Android continues to hold the lead among all smartphone users, with 46.3 percent of all smartphone owners surveyed in Q42011 reporting they have an Android-based mobile phone.

As of Q42011, 46 percent of US mobile consumers had smartphones, and that figure is growing quickly. In fact, 60 percent of those who said they got a new device within the last three months chose a smartphone over a feature phone.

Look to Asymo's "The rise and fall of personal computing" for evidence of how smartphone adoption is disrupting where we as a percentage do our computing.