Phone manufacturers officially begun selling Windows Phone 7 devices in the U.S. this week, less than a year since Microsoft revealed the ground-up redesign of its platform and started pushing the idea of a simpler mobile experience. But perhaps Redmond's odd marketing campaign didn't resonate well with consumers, or the many handset models scrabbling for attention only helped to confuse would-be buyers, as initial sales estimates are not looking pretty.

According to a market research source talking to financial site The Street, Microsoft may have sold as little as 40,000 phones. To put that number into perspective, Apple had some 600,000 pre-orders for the iPhone 4, and is reportedly selling around 270,000 a day. Meanwhile, Google activates some 200,000 Android handsets daily. We're not sure how many Windows Phone 7 handsets were available to begin with - the HTC HD7 reportedly sold out amid "strong interest", and the Venue Pro was only available in limited numbers - but 40,000 seems quite low nevertheless.

It's far too early to forecast another "Kin" failure, though. Microsoft generally gets into new markets for the long run and is prepared to burn a lot of cash to position itself in the market - it persevered with the now profitable Xbox, and less successfully with other ventures such as Zune and Bing. With Apple and Google raking in billions from their mobile platforms, we'll likely see Microsoft sticking around for the fight. It might just take some time to shake off the Windows Mobile stigma.