It may not be officially released until a launch event later on today but Microsoft's Silverlight 3 technology, which adds offline capabilities to the company's rich Internet application platform, is already available for download on the Web.

Silverlight itself is available at this Web page while the SDK can be accessed at this page.  An official launch event for Silverlight 3 and the accompanying Expression Studio 3 design toolset is set for Friday in San Francisco.  A release candidate for the Expression Blend 3 product, for interactive design of user interfaces, also is available at this page and features SketchFlow for rapid prototyping of Web sites.

Silverlight is Microsoft's answer to the established Flash platform for multimedia experiences on the Web. Other features of Silverlight 3 include improvements in audio, video and 3D graphics. Better daata-binding and more controls also have been slated for Silverlight 3.