Did anyone else notice the Store icon on the start screen? I wonder if that will be the primary distribution channel for apps using the new UI. With any luck they'll sandbox apps like they do on Windows Phone 7. No more registry + dll hell.
It's also interesting that they only mentioned HTML5 + JS. Right now Silverlight is the only option for non-games on Windows Phone 7. Given how similar the UIs look, it would be a shame to be unable to share code between mobile and desktop versions of the same app.