According to the graph below, it appears the iOS and the iPhone are taking market share away from BlackBerry and other smartphones. Based on people surveyed that have purchased a smartphone in the past couple months, there is a significant increase in the iOS purchase selection. Android is holding at 48%, but iOS has 32% of all smartphone owners but jumps to 43% looking at those with a more recent purchase decision.
Remember, Microsoft (read Nokia) is preparing to make a significant dent into the iOS and Android marketshare with the Nokia Lumia 900 release to compete with iOS and Android offerings. Sometimes Nielsen is wrong, but this information is certainly interesting.