Microsoft is preparing for the final release of its Windows Phone 7 platform, announcing this week some key milestones leading up to the launch. The final release of the Windows Phone 7 developer tools is slated for September 16, while the Windows Phone Marketplace—through which users will be able to download, try, and buy software applications, apps, games, music, and other media—is set for "early October," Microsoft says.

"It feels like just yesterday that we first introduced Windows Phone 7 to the world," Microsoft's Brandon Watson wrote in a blog post. "Now, just a blink of the eye and phones will be on shelves."

According to Microsoft, over 300,000 developers have downloaded pre-release versions of the Windows Phone 7 developer tools, all of which are and will continue to be made available for free. The tools include Windows Phone-centric versions of the Visual Studio 2010 development environment and the Expression Blend UI designer toolset, along with copious amounts of developer documentation.

In the final version of the developer tools, programmers will get their first peek at two eagerly-awaited constructs, a "panorama pivot," which is used to make sweeping, multiscreen panoramic experiences, or hubs, and the Bing Maps control.

Microsoft also recently announced that some 60-odd Xbox Live games will ship for Windows Phone at launch, and many, many more are expected from independent developers as well. Microsoft has made it very easy for developers to write games that run on Windows, the Xbox 360, and Windows Phone, usually with essentially the same code base. This should lead to a stunning array of cross-platform games that will prop up each of Microsoft's key games platforms.

Windows Phone will be launched broadly in October, according to sources, and internationally by the end of 2010. This week, I'm putting the finishing touches on my latest book, Windows Phone Secrets, which should be available by the October launch.