The open-source Android operating system is gaining momentum, and Microsoft has been slow to respond, says a New York Times report.

The Android system, made by Microsoft rival Google, is used by a dozen cellphone models announced this year, and one maker, HTC, says half its phones sold this year will use the operating system.

All four major carriers offer Android phones, the article notes. Sprint, criticized by open-source fans for not adopting the OS sooner, has the HTC Hero and Samsung Moment among its offerings.

The article also says Microsoft's Windows Mobile system rates poorly in a J.D. Power survey and has been dropped by Motorola in favor of Android.

But while Android is gaining ground with those who like being able to add consumer apps, the Microsoft system still has corporate fans -- it synchronizes well with PCs -- and Android is on less than 2 percent of handsets, according to Gartner.

But Android is offering system updates quickly, and Microsoft has yet to announce a release date for its next full upgrade, Windows Mobile 7.

The full article is here.