Early HTML5-based Windows Phone 7 App Review
The technologies used included:
Here's a video so you can see how an HTML5 app can look and feel very close to the native app experience.
Eberhardt is a major proponent of HTML5 applications for cross-mobile deployment. He's also a Silverlight mobile developer who has frequently shared his experiences using PhoneGap and Knockout.JS for Windows Phone apps. One article introduces the basic concepts and a second one tackles the problem of tombstoning.
Go and check out his full post here. He says he's planning to write a more technical post later on how he made the app.