Today at Mix07 Microsoft is set to announce a a new collaboration service between Silverlight (formerly WPF/E) and Windows Live.

Microsoft® Silverlight™ Streaming by Windows Live™ is a companion service for Silverlight that makes it easier for developers and designers to deliver and scale rich media as part of their Silverlight applications. The service offers web designers and developers a free and convenient solution for hosting and streaming cross-platform, cross-browser media experiences and rich interactive applications that run on Windows™ and Mac. Combined with the ability to create content with Microsoft® Expression Studio and other 3rd party tools, Web designers and content publishers wishing to integrate Silverlight applications into their online properties can enjoy complete control of the end user experience.

Offering 4GB of webhosting for those interested in delivering rich media applications, Silverlight Streaming is currently available in Alpha at http://silverlight.live.com. One thing to note is that while the beta service is free, the final service will offer 1million minutes of free streaming, with the remainder being monetized via advertising or subscription. Silverlight Streaming is perhaps the best example so far on how Microsoft can build a services platform that leverages both desktop applications, 3rd party developer and a services platform. Undoubtably there will be more commentary on this around the web when the announcement is made.

The Silverlight Streaming SDK will be available for download at http://dev.live.com/silverlight later today.