I have just published an article on codeproject which describes the differences in development between Silverlight and HTML5. In order to illustrate the differences, I have re-implemented my Windows Phone 7 JumpList control using HTML5/CSS3. You can see this control in action below:
(NOTE: this will look best in a browser that has support for CSS3 transitions and transformations. Try Google Chrome for example).
The control also works very well on mobile phones with webkit browsers, for example iPhone and Android. See the following video for a demonstration:
Regards, Colin E.