http://team.silverlight.net/announcement/pdc-and-silverlight/
When we started Silverlight, the number of unique/different Internet-connected devices in the world was relatively small, and our goal was to provide the most consistent, richest experience across those devices. But the world has changed. As a result, getting a single runtime implementation installed on every potential device is practically impossible. We think HTML will provide the broadest, cross-platform reach across all these devices. At Microsoft, we’re committed to building the world’s best implementation of HTML 5 for devices running Windows, and at the PDC, we showed the great progress we’re making on this with IE 9.
