Research in Motion’s (RIMM) BlackBerry, with a 40% share, is still the most popular smartphone among the 4,255 owners who responded to a ChangeWave survey in September. But Apple’s (AAPL) iPhone is gaining fast, according to research director Paul Carton.

“Apple (30%) has seen a huge market share jump since the previous survey,” he writes in a release issued Tuesday. “Not only has the iPhone 3GS release enabled them to gain 5-pts overall — for the first time it has also placed them within striking distance of the number one spot in the consumer market.”

Palm (PALM) remains far behind at 7%, Carton notes, but adds that “this is the first survey in nearly two years where their share hasn’t fallen – and that’s a clearly encouraging sign.”

ChangeWave surveys are often dismissed as unrepresentative — which they are. But in this case, the so-called ChangeWave Alliances’ 20,000 professionals “who spend their everyday lives on the frontline of technological change,” according to its website, represent the sweet spot of RIM’s and Palm’s target market.

For more results — good and bad — from the survey, see the charts below the fold.

Apple continues to lead on the customer satisfaction front, with 74% of iPhone owners describing themselves as “very satisfied.”

However, when asked whether they were planning to buy an iPhone, BlackBerry or Pre in the next 90 days, the BlackBerry gained, the Pre held steady and the iPhone fell sharply in comparison with a similar survey conducted in June.

Carton attributes the fall in iPhone purchase plans as a natural “settl[ing] back” after the “huge spike of excitement” that accompanied the iPhone 3GS launch in June. He notes that the 8-pt drop between June and September (from 44% to 36%) is a lot less than the 22-pt drop he picked up a year ago after the July 2008 launch of the iPhone 3G.

[Follow Philip Elmer-DeWitt on Twitter @philiped]