x-ms-webview from WinJS in Windows 8.1 Apps

Blending apps and sites with the HTML x-ms-webview:
"The x-ms-webview is a powerful control that lets you embed web content directly in your app’s UX. This control has been available to XAML Windows Store apps since Windows 8, and in Windows 8.1 ... the control is now available for apps written in HTML and JavaScript!"

This enables embedding web browser view into web-based WinRT apps.
Nice.