Silverlight 4.0.41108 Beta is a Browser Plug-Ins product from microsoft.com, get 5 Stars SoftSea Rating, Silverlight helps you create rich web applications that run on Mac OS, Windows, and Linux. Welcome to a new level of engaging, rich, safe, secure, and scalable cross-platform experience.

Microsoft Silverlight is a cross-browser, cross-platform, and cross-device plug-in for delivering the next generation of .NET based media experiences and rich interactive applications for the Web.

By using Expression Studio and Visual Studio, designers and developers can collaborate more impactfully using the skills they have today to light up the Web of tomorrow.

Custom branded experiences using 2D vector graphics, animation, styling, and skinning
Highly sophisticated RIA's across major browsers on Mac, Windows, Linux, and devices HD video and adaptive streaming techniques for world-class media experiences
Unparalleled interactivity with high resolution content through Deep Zoom technology enabling smooth browsing independent of screen size

Silverlight is essentially nothing more than Microsoft's vision of a cross-browser, cross-platform plug-in designed to be the source of rich online user experiences and to dislodge Flash from its current dominant position on the market. And when the Redmond company said cross-platform they indeed meant it. The license of this internet software is Freeware, you can free download and free use this Internet software.