HTML5, Modernized: Fourth IE9 Platform Preview Available for Developers

IE9 started from the premise that the modern web will deliver HTML5 experiences that feel more like native applications than sites. Building on hardware-accelerated SVG, canvas, video, audio, and text, developers will use the power of the whole PC to achieve great performance. On the modern web, developers will use the same markup across different HTML5 browsers.
Fully Hardware-Accelerated HTML5

Modern SVG
Native JavaScript Integration
Same Markup, and Tests
Getting sites ready for Beta
Platform Preview 4 is an important milestone on the way to beta. It is the last preview before the IE9 Beta. The IE9 platform is nearly complete.