Some folks at Microsoft are just great. Take Mads Kristensen and some folks in his team: last week they released a free update to Visual Studio 2010 SP1 that delivers better support for writing standards web pages. In essence, the extension adds Intellisense support for HTML5 and CSS3, following the newest W3C specs as good as possible.
This includes schema support for Video, Audio, Input Type, Drag & Drop, WAI-ARIA, Microdata, Schema.org; intellisense for DOM API for Geolocation and Local storage; CSS3 support for 2D transforms, 3D transforms, flexbox model, media queries and loads more . CSS3 vendor prefixes -ms, -webkit and -moz are also included.

What about the free Visual Web Developer Express 2010 version? No problem, you can also take advantage of this extension with Web Developer Express 2010 SP1.

Next steps:

Note: because it’s created by these guys in their spare time, do note this is not an officially supported update.