Silverlight 3 Beta

http://silverlight.net/getstarted/silverlight3/default.aspx

Silverlight 3 Beta was unveiled at MIX09. It is a preview release which continues Silverlight’s track record of rapid innovation - introducing more than 50 new features, including support for running Silverlight applications out of the browser, dramatic video performance and quality improvements, and features that radically improve developer productivity.

Important notes:

• This is a developer beta release only! This means there is no “go-live” licensing available and the end-user runtime of Silverlight 3 is not available. The tools below are intended for software developers only.
• Once you install the Silverlight 3 Beta Tools for Visual Studio, your development environment will be a Silverlight 3 Beta environment.  Visual Studio 2008 SP1 does not support multi-targeting for Silverlight applications so you will be unable to develop Silverlight 2 applications once these tools are installed.  We recommend that you install the Silverlight 3 Beta tools on a separate environment if you still need to have the ability to develop Silverlight 2 applications.
• Ensure that you have either Visual Studio 2008 SP1 or Visual Web Developer Express 2008 SP1 installed as it is a prerequisite for the Silverlight 3 Beta Tools for Visual Studio.