Internet Explorer 10 in the Windows Consumer Preview introduces a number of new or updated Web platform features when compared to the IE10 in the Windows Developer Preview released September 13, 2011. Some of these shipped in the fourth IE10 platform preview released November 29, 2011, and have been blogged about since; some are new in the Consumer Preview.
New or Updated Web Platform Features

The following Web platform capabilities in the Consumer Preview were not in the Developer Preview:
  • Cross-Origin Resource Sharing (CORS) for XMLHttpRequest (spec / post / dev guide)
  • CSS -ms-user-select property (post / dev guide)
  • CSS3 font-feature-settings property to access advanced OpenType® features (spec / post / dev guide)
  • Document setting to enable floating point values in CSS-OM (post / dev guide)
  • HTML5 BlobBuilder API and new APIs to save or open files (spec*/*post*/*dev guide)
  • HTML5 track element for HTML5 video captions (spec*/ post / dev guide)
  • Interoperable HTML5 Quirks mode (post / dev guide)
  • JavaScript Typed Arrays (post)
  • Meta tag to alert user that site requires ActiveX add-ons available only in desktop IE10 (post)
  • Removal of legacy graphics features from IE10 standards mode (post)
  • Changes to support latest HTML5 WebSocket API (spec)
  • Web Worker thread pooling
Across the board, we’ve improved performance and addressed feedback on the platform features that were available in the Windows Developer Preview but not IE9:
More to Come: User Interface Improvements

Metro style Internet Explorer in the Windows Consumer Preview contains many user interface changes and additions compared to the Windows Developer Preview. You can get a taste for these in what Gizmodo wrote about Internet Explorer 10. We will be blogging about these new features in the coming days both here and on Building Windows 8.
—Ted Johnson for IEBlog