Internet Explorer 10 Platform Preview 4 is now available for download and testing. This IE10 preview 4 adds more support for HTML5 technologies.
Cross-Origin Resource Sharing (CORS) for safe use of XMLHttpRequest across domains.
File API Writer support for blobBuilder allowing manipulation of large binary objects in script in the browser.
CSS user-select property to control how end-users select elements in a Web page or application.
Support for HTML5 video text captioning, including time-code, placement, and captioning file formats
Internet Explorer 10 Platform Preview 4