Microsoft Silverlight 5.1.50918.0

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.
Microsoft revealed that it does not plan to leverage the existing Windows Update infrastructure in order to make available Silverlight to all users of the Windows operating system. Such a move would give Silverlight immediate and total access to an install base close to 1 billion users and will make it just as ubiquitous as Adobe's Flash. Instead the Redmond company has debuted a number of in-house projects to push the technology, as well as tap its partners for support.