The competition between smartphones in the US has effectively devolved into a race between Apple and Research in Motion, a new ChangeWave survey suggests. A March poll of over 3,500 shoppers indicates that while the marketshare of RIM's BlackBerry phones has slid 1 percent since January, it still maintains an overwhelming dominance at a total of 42 percent. Apple's iPhone, meanwhile, has flourished since its June 2007 debut to occupy 9 percent of the market. Treo maker Palm occupies second place at 16 percent, but has been in a continual decline since June of 2006, plummeting from a once-leading position of 36 percent.

The position of the iPhone as a BlackBerry competitor is tied to its expected ascendancy. Of those planning to buy a smartphone in the next 90 days, 35 percent of poll respondents said they would be choosing the iPhone. This is a 12 percent gain over January, attributed to 1 in 10 respondents saying they were more likely to buy because of the SDK and the v2.0 firmware, both of which are due in June.

Apple already dominates in terms of customer satisfaction, with 79 percent of iPhone owners in the survey having said they are "very satisfied." BlackBerries produced this happiness for 54 percent of owners, while Palm's ranking was a low 22 percent.