Metro is a set of UI guidelines, not a set of programming tools. Applications built using the Silverlight Framework (not to be confused with the browser plugin) should be suitable for cross platform development because CLR runs on both platforms. CLR remains Microsoft's way of integrating the "write once, run anywhere" philosophy within the Windows ecosystem in order to deal with legacy issues.

Thanks. This whole stack is very confusing to me these days (I once was a Windows developer, one of the first MCPs in Brazil, but that was another life, a very long time ago).

And Android, iOS and OSX are all waiting in line for my attention before I consider learning modern Windows development again. I sincerely hope that, if I wait long enough, I won't need to ;-)

Are you sure you're not describing cross-platform with Windows Phone instead of Windows 8?

I thought for Windows 8, Microsoft is pushing WinRT as the cross-platform solution, and that "binaries" crossing from x86/x64 to arm will work as-is for javascript, as-is (if pure) for CLR, and with no modifications but requiring recompilation for native (C/C++) WinRT apps.

If you're writing in C/C++ rather than C#, then you're off the CLR ranch, so to speak. It's like saying Java isn't portable because a program links to custom libraries written in C.

That said, rumor has it that the next version of Windows Phone will not be Silverlight (though XAML and Silverlight are fairly similar), but based on WinRT.

That's a good thing because it will allow Windows Phone Apps to better integrate Javascript.

>The only apps that will be cross-platform will be WinRT/Metro based ones.

Is this true? The code is cross-platform, but I was under the impression that the executable was not. You still need to compile the app for both X86 and ARM.