>Cross platform .NET usually means using a native toolkit on each different platform and the result is WPF on Windows, GTK# on Linux, and MonoMac on Mac.
What are the odds Microsoft announces WPF open sourcing and maybe a wrapper of some sorts for OSX support at Build this year? I give it at least 50/50 on the open sourcing part.
AFAIK WPF is managed by the Windows team. All this open sourcing has been happening form the Azure and developer teams. Chances of Windows open sourcing some of their code? Less likely.
As someone who worked on WPF though, I will comment that the code may not actually be too useful. It is heavily tied to Windows and its graphics infrastructure.
I'm more interested in seeing something like Moonlight ported to modern platforms.
WPF is very heavily tied into DirectX and other Windows-only APIs.
Open Sourcing it is one thing, converting that into an engine that can do layout and rendering identically across multiple platforms is non-trivially difficult. Talk to the browser folks on how hard they had to work on that, and they wern't dealing with 3D stuff.
Windows RT (aka Metro, aka Store Apps). It's a model based on WPF but not fully compliant - it took in lessons learned form Silverlight. Call it WPFlight.
That's the toolkit if you want Metro apps, dealing with MS's crappy store, etc. etc. If you want a traditional Windows application that just works, then WPF is fine. (And I think WPF has an option for non-blurry text rendering, whereas every Metro app seems to be blurry.)
Okay, yeah, so still XAML. I've only recently looked into Windows RT, my time was always spent in ASP.NET, so WPF/WinRT/Silverlight, it all seems like the same thing to me, but I do know a lot of Windows app developers that bitch up a storm about the diffs between WinRT XAML and what can be done in WPF :)
