Riding the wave of new handset introductions and wide carrier distribution in the second quarter (Q2), the Android smartphone operating system (OS) continued its upward climb in the U.S. consumer mobile phone market, according to The NPD Group (http://www.npd.com), a market research company.

For the first time since the fourth quarter (Q4) of 2007, RIM fell to second position, as Android took the lead among operating systems in handsets sold to U.S. consumers. NPD’s latest wireless market research reveals that Android accounted for 33% of all smartphones purchased in Q2, ahead of RIM (28 %) and Apple (22%).

"For the second consecutive quarter, Android handsets have shown strong but slowing sell-through market share gains among U.S. consumers," says Ross Rubin, executive director of industry analysis for NPD. "While the Google-developed OS took market share from RIM, Apple’s iOS saw a small gain this quarter on the strength of the iPhone 4 launch."

According to NPD’s Mobile Phone Track, Verizon Wireless has maintained its lead among top carriers for the last three quarters comprising a third (33%) of the units sold in the U.S. mobile phone market in Q2, followed by AT&T (25%), Sprint (12%), and T-Mobile (11%). In Q2 Verizon Wireless continued their buy-one-get-one (BOGO) offers on all smartphones, including both RIM and Android models.

In spite of an overall decline in the number of mobile phones purchased year over year, the ongoing popularity of both messaging phones and smartphones, which are generally more costly than standard feature phones, resulted in slightly higher prices for all mobile phones in Q2. The average selling price for all mobile phones reached US$90, which is a 3% increase since Q2 last year. Smartphone unit prices, by comparison, averaged $143 in Q2 2010, whic