New references to an “Immersive Shell” inside Windows 8 were revealed on Friday.
The references point towards Microsoft’s secondary interface for Windows 8. The second interface will be used as the primary interaction point for touch based hardware. Geeksmack posted a number of references from Windows 8 build 7959. The existences of Internet Explorer integration, tiles, dock and a notification system have all been confirmed.
The “immersive” experience will include a Metro based user interface according to sources familiar with Microsoft’s plans. Microsoft will include a new application model codenamed “Jupiter” that will allow developers to create Silverlight based applications, deployed as AppX packages (.appx). The packages will be part of a new Windows application store, pre-installed with Windows 8. WinRumors understands the company will be looking to provide an easy way for existing Windows Phone developers to scale their applications for use with Jupiter.
Separately, Winreview also posted a number of “Immersive” traces on Friday. The resources appear to confirm some of the Metro UI elements that will make their way into Microsoft’s Tablet experience.

Windows 8 "Immersive" UI for Tablets