Yesterday, Microsoft announced the availability of Silverlight 4 Tools for Visual Studio 2010. The add-on provides support for a number of Silverlight capabilities within both Visual Studio 2010 and Visual Web Developer Express.
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The project blog post also notes, “Many of the new designer features work well with WPF (Windows Presentation Foundation) as well as Silverlight projects, so this download is definitely recommended for Visual Studio 2010 WPF designer users too.”