So what if Windows Phone 7 doesn't have the allure of the iPhone? The device is selling well, and that's a problem for Research In Motion (Nasdaq: RIMM) and Nokia (NYSE: NOK).

In a Q&A posted earlier this week, Microsoft (Nasdaq: MSFT) executive Achim Berg said manufacturers had sold 1.5 million Windows Phone 7 handsets in the operating system's first six weeks of release. More than 4,000 apps are now live in the Windows Phone 7 marketplace.

No doubt those numbers sound small when compared with the hundreds of thousands of iPhones and Android handsets activated daily. So be it. No one, not even Microsoft, is pretending that Windows Phone 7 is in a position to dethrone Apple (Nasdaq: AAPL) or Google (Nasdaq: GOOG) as princes of the mobile-telephony realm. All Berg wants is progress, which he says he's getting.

"Sales are ramping well as our reputation is growing for offering users a unique experience and are in line with our expectations -- especially when compared to other new platform introductions," Berg said in the Q&A.

We've already seen evidence of momentum. Last month, Dell (Nasdaq: DELL), which already produces Android handsets, announced plans to switch 25,000 employees from the BlackBerry to Windows Phone 7 handsets.

What's less clear is how much impact Windows Phone 7 will have on mobile OS usage. But it's a good bet that RIM and Nokia have the most to lose from Mr. Softy's renewed emphasis on mobile telephony. Gartner data shows both OSes losing ground:


 

To be fair, so have Microsoft and Apple now that Android has become a juggernaut. But Mr. Softy's losses also came at the expense of the aging Windows Mobile platform, which frankly should have died a long time ago.

Windows Phone 7 isn't the same platform. It's better, it's more fun, and it's winning converts. Look out, RIM. Stay sharp, Nokia. Microsoft is coming for you both.

Now it's your turn to weigh in. Is Windows Phone 7 as big a threat as it appears to be? Please vote in the poll below, and then leave a comment to explain your thinking. You can also rate Microsoft in Motley Fool CAPS.

Interested in more info on the stocks mentioned in this story? Add Research In Motion, Nokia, Microsoft, Apple, Google, or Dell to your watchlist.

Google and Microsoft are Motley Fool Inside Value picks. Google is also a Motley Fool Rule Breakers recommendation. Apple is a Motley Fool Stock Advisor selection. Motley Fool Options has recommended subscribers open a diagonal call position in Microsoft. Try any of our Foolish newsletter services free for 30 days.

Fool contributor Tim Beyers is a member of the Rule Breakers stock-picking team. He had stock and options positions in Apple and a stock position in Google at the time of publication. Check out Tim's portfolio holdings and Foolish writings, or connect with him on Twitter as @milehighfool. You can also get his insights delivered directly to your RSS reader. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool owns shares of Apple, Google, and Microsoft and is also on Twitter as @TheMotleyFool. Its disclosure policy waited till college to take an archery class.