More information on Windows 8 is leaking out now; and it gives some clues about how Microsoft intends to make sense of its two device platforms, Windows tablets and Windows Phone.

Microsoft held back from making its Windows Phone 7 OS available on tablets, which is why most of the numerous tablets being pushed out to compete with Apple run Google Android, and a few of them Windows 7 with its excessive power requirements and a user interface poorly designed for touch control.

Now the strong rumour is that Windows 8 supports two user interfaces, one that is tile-based like Windows Phone 7, and another that is designed for PCs.

In other words, rather than continuing with the Windows Phone 7 OS which is built on Windows CE, Microsoft will build a new version of the Windows Phone 7 UI on top of full Windows.

My further assumption is that Silverlight apps will still run on the new OS, providing continuity with Windows Phone 7 which uses Silverlight or XNA, both based on .NET, for its application platform.

Silverlight might also be used as the platform for apps delivered by the new Windows app store. This is Paul Thurrott, though reported as rumour:

Windows 8 will also include a new app model codenamed Jupiter that will target a new Windows Marketplace app store. 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. These apps can be written in C#, Visual Basic, and even C++.

We do know that Silverlight 5 supports full platform invoke of native code, a feature which tends to support the idea that it is becoming a key runtime for Windows.

Let me speculate a little further. Imagine you are Adobe, for example, which has said it will deliver the Flash runtime for Windows Phone. Although it competes with Silverlight to some extent, Microsoft needs to tick the Flash box for Windows Phone. But why would Adobe want to invest in Flash for Windows CE, when this OS is not going to be used for Windows Phone 8 and it will have to write new code? I will not be surprised if we hear that Flash is now not coming until Windows Phone 8.

Even within Microsoft itself, I would guess that investment is focused on the next generation rather than the one that is destined to be short-lived.

One partner that is no doubt close to Microsoft’s plans is Nokia. If the above is correct, then Nokia is buying into the Windows OS, not the Windows Phone OS. Will Nokia wait for Windows Phone 8 before launching devices on the platform? I have no idea – and delay will be costly – but I imagine its main plans will be focused on Windows Phone 8 and the possibility of tablet as well as smartphone devices.

The immediate conclusions would be:

• Silverlight is safe as a development platform, but only for Windows. See also Silverlight the new Windows runtime, HTML 5 the new Silverlight?
• The Windows Phone 7 OS will be short-lived but the new UI should be a natural progression from what we have now, and apps should still run, so Microsoft can position Windows Phone 8 to users as a new version of Windows Phone rather than a change of direction.
• Microsoft will not have a coherent mobile and tablet platform until Windows 8 ships sometime in 2012. Google, Apple, RIM, HP, all have plenty of time to establish their competing platforms.