I'm a bit confused by the wording in the OP. I don't have any exposure to XNA (which is a completely different framework from Silverlight), but my basic understanding of the situation:
In short: XAML/C# is Silverlight now, and similar to the XAML/C# used in WinRT/WP8.
C# code will always be managed, you can throw in native C/C++ as necessary.
I suspect XNA is going to disappear, since there's no XNA support in WinRT. I've got no idea what kind of carry-over there is from XNA to directx games.
The Coding4Fun peeps seem to be doing some nice work.
Also here.. There building-out a lot of interesting/useful things.
Damn. thx for letting me know.
If you have a sec, do either of these work? 1. http://jquerymobile.com/demos/1.0a4.1/ 2. http://jquerymobile.com/test/
The mobile web app is built using jQueryMobile, it may have an incompatibility with wp7.