Microsoft has released the "Mango" Windows Phone 7 update to its device manufacturing partners

Microsoft announced yesterday that the newest version of the Windows Phone 7, code-named “Mango,” has reached the release to manufacturing (RTM) stage.

The RTM stage marks the end of Microsoft’s development of the mobile OS. Original equipment manufacturers (OEMs) can now start incorporating the mobile operating system update into their new smartphone products.

“Here on the Windows Phone team, we now turn to preparing for the update process,” Microsoft Windows Phone chief Terry Myerson said in The Windows Blog. “The Mango update for current Windows Phone handsets will be ready this fall, and of course will come pre-installed on new Windows Phones.”

Despite the new release and a major partnership with Nokia, the Windows developer still faces a tough battle in its quest to reclaim market share in mobile. Apple and Google’s mobile operating systems, iOS and Android respectively, are still the dominant forces in the market, though some predict that WP7 will gain traction in the next few years.

Japan to Get The World’s First Windows Phone 7

Even though Microsoft has forecast the fall arrival of Mango, that expectation might not be valid in Japan.

Japanese IT services company Fujitsu and telecommunications operator KDDI have just confirmed that they will launch the world’s first phone running Mango sometime in September. Exact details surrounding the handset are still developing, but all signs are pointing to it being the Toshiba-Fujitsu IS12T device that Microsoft gave a very brief sneak peak of at their Worldwide Partner Conference just a few weeks back.

Microsoft did not clarify by press time whether the launch and availability timeline for Mango in Japan might also be reflected in U.S. markets. Via a spokesperson, Microsoft issued this statement: “We are on track to deliver Mango later this year. Stay tuned for more news as we get closer to that time.”