Article from arstechnica.com
Two weeks after the operating system itself was finalized, Microsoft has released the Windows Phone 7 SDK to developers. Applications developed with the new SDK will be submittable to the Windows Phone Marketplace when that opens for submissions next month.
The new SDK brings many welcome improvements; it (finally) includes built-in support to allow developers to offer many of the same interface concepts as the built-in phone software uses. Specifically, Panoramas, used in the various hubs such as People and Office, and Pivots, used in the e-mail client, are now available for all to use. The sideways-scrolling panoramas in particular are a striking part of the Windows Phone 7 experience, and their absence led many to attempt to develop their own versions. Having a standard control to use will ease development and provide greater uniformity in third-party applications.
In spite of these additions, the SDK still isn't complete. There are desirable things that the built-in applications include—such as picking dates and times—that aren't available to third parties. In spite of the work that Microsoft has put in to Windows Phone 7 over the last few months of public releases, it's still a new platform that's immature in many ways.
To fill some of these gaps, the company is using its open source Silverlight Toolkit project to provide unsupported alternatives to the missing functionality.
In addition to the main SDK, Microsoft also released a Mobile Advertising SDK. Microsoft already has its own advertising platform, used in Bing (and soon Yahoo!), and unsurprisingly, it's bringing it to its mobile platform—for some months, Redmond has been promoting its phone operating system as an "ad-serving machine." With the SDK, it's trivial for developers to add advertising to their applications as a way of monetizing them.
Initially, the ads will only be available in the US, to US developers. Support in other markets will begin rolling out early next year. With Windows Phone 7 launching first in Europe, this is a little surprising. Microsoft already sells ads outside the US, and can pay non-US developers of phone apps, so on the face of it, it would seem that all the legal hurdles have been jumped, giving little reason for such a restriction. The first ads will be plain text and image banners, with rich media ads—similar to those of Apple's iAd—promised for the future. Microsoft's ads will pay out 70 percent of ad revenue to the application publisher, in contrast to iAd's 60 percent.
In a Bieber-heavy demo, Microsoft's Brandon Watson also showed off Windows Phone 7's YouTube support. Surprisingly, this used neither a YouTube application nor Flash (which is not available on the platform at the moment). Instead, Windows Phone 7 streamed the videos directly from YouTube using YouTube's APIs for that purpose; the support is built-in. YouTube videos also appear to integrate into the operating system's hubs, putting them on an equal footing with videos stored on the device itself.