HTML5 Support for the Visual Studio 2010 Editor
The first Web Standards Update for Visual Studio 2010 SP1 is available for download, you can get it here: http://visualstudiogallery.msdn.microsoft.com/a15c3ce9-f58f-42b7-8668-53f6cdc2cd83

We just released the first Web Standards Update for Visual Studio 2010 SP1. Despite its name, the update also works for Visual Web Developer Express 2010 SP1. You can read more on our team blog.

In this first release of the update, we have focused on bringing the HTML5 support up-to-date, adding CSS 3 support and bring more new API’s to the JavaScript intellisense. The plan is to make a release about every 3 months to keep Visual Studio updated with the changes made by W3C.

Here are some of the features that the Visual Studio Web Standards Update provides you with intellisense and validation for
HTML 5 features

Video & related tags
Audio & related tag
New input types like email, url, date etc
Drag & Drop support
Accessibility standard WAI-ARIA
Microdata
Schema.org

CSS3

2D Transforms
3D Transforms
Animations
Background & Borders
Basic Box Model
Basic UI
Behavior
Color
Flexible Box Layout
Fonts
Generated Content for Paged Media
Hyperlink Presentation
Line
Lists
Marquee
Media Queries
Multi Column
Namespaces
Paged Media
Presentations Levels
Ruby
Selectors
Speech
Syntax
Template Layout
Text
Transitions

Download it here: http://visualstudiogallery.msdn.microsoft.com/a15c3ce9-f58f-42b7-8668-53f6cdc2cd83

Read more about it here: http://blogs.msdn.com/b/webdevtools/archive/2011/06/15/web-standards-update-for-visual-studio-2010-sp1.aspx