The 4,413 consumers polled in ChangeWave Research’s March survey are not exactly a representative cross-section of the buying public. They’re primarily American (87%) and almost all early-adopter types. But as ChangeWave members they do tend to indicate which way the technological wind is blowing.

And according the bar chart above, it’s blowing Apple’s (AAPL) way. Despite growing competition and rumors that the company may be releasing a new model next fall, 56% of the respondents who plan to buy a smartphone in the next three months plan to buy an iPhone — up 2 percentage points from the last survey, taken at the height of the holiday shopping season.

That 56%, research director Paul Carton notes, is the second highest his firm — a division of 451 Research — has ever recorded — second only to a survey taken just before the iPhone 4S was launched last fall. (See chart below.)

In the same December to March period, Motorola’s (MOT) demand in this group was down, Samsung’s and HTC’s were flat and Research in Motion (RIMM), against all odds, was actually up a point.