Silverlight 4 Tools for Visual Studio

追記(7:35)

以下のMSダウンロードよりダウンロードください。内容的には以下のようになるようです。

Instructions

This package is an add-on for Visual Studio 2010 to provide tooling for Microsoft Silverlight 4 and RIA Services. It can be installed on top of either Visual Studio 2010 or Visual Web Developer 2010 Express. It extends existing Silverlight 3 features and multitargeting capabilities in Visual Studio 2010 to also create applications for Silverlight 4 using C# or Visual Basic.
Silverlight 4 Tools for Visual Studio 2010 includes several features:

• Support for targeting Silverlight 4 in the Silverlight designer and project system
• RIA Services application templates and libraries
• Support for Silverlight 4 elevated trust and out-of-browser applications and other new Silverlight 4 features

This download will install all components necessary for Silverlight 4 and RIA Services development:

• Silverlight 4 developer runtime (final release)
• Silverlight 4 SDK (software development kit, final release)
• Update for Visual Studio 2010 and Visual Web Developer Express 2010 (KB976272, pre-release)
• Silverlight 4 Tools for Visual Studio 2010 RC2
• WCF RIA Services for Silverlight 4 RC2

The final release of Silverlight 4 Tools will be made available in the near future.

Microsoft Silverlight 4 Tools for Visual Studio 2010
http://www.microsoft.com/downloads/details.aspx?displaylang=en&FamilyID=bf5ab940-c011-4bd1-ad98-da671e491009

RuntimeはRTM、ToolsはRC2という状態ですね。

追記：以下のリンク先が修正されていないようで、ダウンロードできたのはBeta2のものだったようです。

以下のページからダウンロードできます。

Get Started : The Official Microsoft Silverlight Site

ここで対象をクリック！ということですね。