Nice…after many years of trying to get coding students to understand why one can’t directly access cross-domain resources and Web security students to understand its implications, the fourth IE10 Platform Preview features, amongst other things, support for CORS (cross-origin resource sharing). The full highlight list of HTML5-affected updates to IE can be found here but I am particularly gung-ho for the CORS and the video text captioning (which was always difficult in the past). It’s not that CORS wasn’t available in other browsers, particularly assisted by the including in the recent jQuery builds, but at least this sets the stage for better cross-browser compatibility in HTML5 applications.
Here’s a post on MSDN by Rob Mauceri with more details…