Today, research firm NPD released its new mobile phone track report for the second quarter of 2011. The report shows that Android continues to lead the U.S. smartphone market with 52% of new sales during the quarter. iPhone accounted for 29% of the market while Research in Motion’s BlackBerry continued to decline and only accounted for 11% of the market.

SplatF points out that Apple’s 14 month-old iPhone 4 continues to lead the market in sales. In addition, the 8 GB iPhone 3GS ranks second. Apple’s iPhone 3GS was introduced 26 monnths ago, and they have kept the device available for purchase following last year’s iPhone 4 introduction by dropping the capacity to 8 GB and price to $99. Pricing for the iPhone 3GS has dropped to $49 since then.

Here are the top five best-selling phones during Q2, via NPD’s Mobile Phone Track service:

1. Apple iPhone 4
2. Apple iPhone 3GS
3. HTC EVO 4G
4. HTC Inspire 4G
5. Samsung INTENSITYII

Apple has continued to keep the iPhone 4 traction going by introducing a CDMA version on Verizon and the launch of the white iPhone 4. The company is expected to release a new version of the iPhone at the end of September or early October, and is expected to offer a lower end version of the iPhone 4.

If you were to ask me, for a phone that has be pronounced “dead in the water” many times, these results are shocking.