Almost one in three who purchased Apple’s iPhone 3G in the U.S. from June to August switched from another carrier to join AT&T (NYSE: T), according to a new report from The NPD Group. Moreover, the firm concluded that Apple (NSDQ: AAPL) commanded 17 percent of the smartphone market at the end of August, up from an 11 percent share prior to the iPhone 3G launch. The amount of iPhone 3G customers coming from other carriers (30 percent) may appear significant, but the firm’s survey also found that 23 percent of all wireless subscribers in the U.S. switched carriers during the same period. Almost half of the new AT&T iPhone customers switched from Verizon Wireless (NYSE: VZ), 24 percent switched from T-Mobile and 19 percent switched from Sprint (NYSE: S) Nextel. Average smartphone prices have also dropped 26 percent from a year ago to $174. Release. Also, according to some creative calculations based on unique ID numbers culled from iPhone owners, analysis indicates Apple hit its goal of selling 10 million iPhones in 2008 with three months to spare, Fortune reports.

NPD says the top four selling smartphones between June and August are:
1. Apple iPhone 3G
2. RIM (NSDQ: RIMM) Blackberry Curve
3. RIM Blackberry Pearl
4. Palm (NSDQ: PALM) Centro