Microsoft has released a new test build of Internet Explorer 10. This version (The Platform Preview 4 (PP4) release ) only works on Windows 8.
This is not an update to the Platform Preview of IE 10 on Windows 7 but this release is for IE 10 on the Developer Preview pre-beta build of Windows 8 only.
IE 10 PP4 is said to add even more support for HTML5 technologies, enabling richer Web applications.
Some of the additions: