• by Mark Walsh  @markfwal, September 20, 2011

Android's explosive growth may be leveling off, but the Google mobile operating system is still the one consumers want to power their phones.

According to new findings from market research firm NPD Group, Android is the preferred operating system among current smartphone owners who plan to buy a phone in the next six months. It not only generates more interest than any other OS (63%), but is also the platform people said they were "most interested in," at 36%.

Android's continuing appeal spells trouble for some of its rivals, noted Linda Barrabee, research director for NPD's Connected Intelligence service. "For example, one-third of BlackBerry smartphone owners are most interested in Android for their next smartphone purchase," she said. The "Android: Variation and Value-Add" report also points out that the Google OS comprises at least half of all smartphone purchases for the last three quarters.

Even so, it suggests Android's dominance is not guaranteed. For one thing, there is continued competition from the iPhone, the latest version of which is expected to roll out next month. "Apple's overall share may indeed grow, given that it is likely that Verizon will have a last-generation model, akin to what AT&T now has with the 3GS, which is still selling well," said Barrabee.

The iPhone had a 27% share of the U.S. market among smartphone platforms for the three months ending in July, second to Android's 42% share, according to comScore.

But Barrabee added that it's difficult to gauge the iPhone 5's impact without knowing exactly what it will look like and what type of data plans and carrier marketing it will have relative to competitors.

Microsoft's Windows Phone 7 platform, which so far has failed to get Microsoft back in the smartphone game, could get a boost from the imminent release this fall of new devices equipped with the upgraded version of WP7, code-named "Mango." NPD found that 44% of smartphone users -- and those who intend to buy one -- are considering purchasing a WP7 device.

With only 5.7% share of the U.S. market, the Microsoft platform is significantly behind Android. Despite the company's ad blitz last year for the Windows Phone launch, awareness remains a problem. Only 45% of consumers know about WP7, per NPD.

"Windows Phone 7 has a way to go before consumers really understand what it is," said Barrabee. "But with the right marketing mojo, apps portfolio and feature-rich hardware, Microsoft could certainly improve its standing and chip away at Android's dominant market position."

There is ample chipping to do before it even gets close to threatening the Google OS.