In one of its quieter launches, Microsoft has made Silverlight 5 available for download, and rumors suggest this may be the last major upgrade for the code.

Among the full list of improvements are hardware decoding of H.264 unprotected content using the GPU, support for 64-bit browsers and a rewritten graphics stack using built-in XNA Games Studio 4.0 graphics libraries for vertex shading and basic 3D. New sound effects and a variable video replay rate have also been added.

Postscript Vector printing is now supported, which should improve the finished product and help reduce file sizes. Text handling has seen several additions, including the character spacing and support for RichTextBlock and OpenType.

Silverlight 5 is also using a new Trusted Application model from Redmond, which uses “a group policy registry key and an application certificate, meaning users won’t need to leave the browser to perform complex tasks such as multiple window support, full trust support in browser including COM and file system access, in browser HTML hosting within Silverlight, and P/Invoke support for existing native code to be run directly from Silverlight,” the team said on its blog.

There has been speculation that this could be the last version of Silverlight Microsoft ships, after redundancies on the team and questions raised over the company’s commitment to cross-browser support and developer relations. Redmond is saying it will support this build until 2021, and is still winning new customers, so there may be life in the old dog yet. ®