To quote Scott Hanselman….
Visual Studio 2010 is really extensible and that's allowed many folks on the team to try out new features for Web Development without having to rebuild Visual Studio itself. One of those "playground" extensions is called "Web Essentials" by Mads Kristensen. Mads handles HTML5 and CSS3 tools for our team. You might remember Mads from when we released the Web Standards Update a few months back.
Get it here: Scott Nanselman blog...