No HTML 5 Support for Windows Phone 7
On the Windows Phone 7 front, Microsoft says that there is no plan currently to bring HTML 5 support to Internet Explorer Mobile. The mobile browser, which has been re-written for the next-generation operating system, is based in large part off of the desktop editions of Internet Explorer 7 and 8; Internet Explorer 9 for Windows does support HTML 5.
For some good news, Microsoft says that it is still partnering up with Adobe to bring the Flash browser plugin to Windows Phone 7 in about half a year or so. According to Microsoft Technology Evangelist Frank Prengel, the company is waiting on Adobe to iron out any kinks for the final version of the plugin.