The tile-based interface would appear to be similar to what's currently available on Windows Phone 7, but without any details - let alone screenshots - it's impossible to tell. According to Paul Thurrot, the interface is codenamed Mosh, and will only be available on devices like tablets. In other words, it's not a replacement, but an alternative.
All this seems to fit with the idea that Microsoft is trying to consolidate all form factors into one - as in, everything will be running Windows NT, no matter the screen size, no matter the architecture. Not only would this be a serious cost-cutting measure, but it would also allow for faster propagation of new lower-level features throughout all the different form-factors currently supported by Windows NT and Windows CE. In other words, it's the Linux strategy.
The rumours around Jupiter are possibly more interesting. "Windows 8 will also include a new app model codenamed Jupiter that will target a new Windows Marketplace app store," Thurrot claims, "The app store will provide access to new, Silverlight-based 'immersive' applications that are deployed as AppX packages (.appx)."
"The Windows and Office teams are betting very heavily on this new app type, according to my source, and development has already begun using a beta version of Visual Studio 2012," he adds, "These apps can be written in C#, Visual Basic, and even C++."
The Jupiter rumours were confirmed by another Microsoft insider, Mary-Jo Foley. After talking to a few of her sources inside the company, she's gained a pretty decent insight into what Jupiter actually is.
"Jupiter is going to be a new user interface library for Windows, built alongside Windows 8. It will be a thin XAML/UI layer on top of Windows application programming interfaces and frameworks for subsystems like graphics, text and input," she details, "The idea is Jupiter will bring support for smoother and more fluid animation, rich typography, and new media capabilities to Windows 8 devices."
As Tess, Kroc, and I already discussed in the podcast, it seems like to me that Microsoft might be using this as a means to coerce developers away from the current development models of Windows. All they need to do is include the Marketplace application store with every copy of Windows 8, and limit the store to Jupiter applications only. Then, detail that for Windows 9, the various application stores - Windows Phone, Xbox, and Windows (and Surface?) - will be unified, and you've got a pretty decent audience for developers to target.
Of course, we won't know anything for sure until Steven Sinofsky allows for the veil to be lifted, but in all honesty, it looks like as if Microsoft's Windows strategy is finally culminating into something good. This process started with the slow untangling of the Windows codebase somewhere around 2002 and 2003, and it looks like it will culminate into Windows NT everywhere, Silverlight/.Net everywhere, all served by a single, unified application store.
And thus, backwards compatibility would cease to be a major issue.