Microsoft® Silverlight™ is a cross-browser, cross-platform plug-in for delivering the next generation of .NET based media experiences and rich interactive applications for the Web.
[1]
Video: Silverlight in Action [2]
Silverlight offers a flexible programming model that supports AJAX, VB, C#, Python, and Ruby, and integrates with existing Web applications. Silverlight supports fast, cost-effective delivery of high-quality video to all major browsers running on the Mac OS or Windows.
Links:
[1] http://go.microsoft.com/fwlink/?LinkID=89241&clcid=0x409
[2] http://download.microsoft.com/download/2/C/4/2C433161-F56C-4BAB-BBC5-B8C6F240AFCC/SL_0410_448x256_300kb_2passCBR.wmv
[3] http://silverlight.net/