I downloaded the latest xamlon beta ... it Rocks!
For one, they've got a really nifty little XAML editor called XamlPad. Simply author your Xaml in the editor and press F5 to execute it. If they could find a way to support a code-behind (or whatever they're calling it in longhorn terms) it could really stand the test of time. Maybe something like a split screen with xaml and C# code ... programmatically compiling and loading the code is easy enough.
For two, they've got 3D support now! it's still kind of basic, but the fact remains that they are really keeping up with what's currently public, I am really impressed.
In preparation for the 3D fun I'm about to have, I downloaded Ian Griffith's DxMeshToXaml. The tool outputs to stdout (ie. the command line for you non command-line folk) ... if you want a file to work with, simply redirect stdout to a file
DxMeshToXaml.exe myobject.x > myobject.xaml
And to make it even easier to work with, if you add the directory that the exe lives in to the Path system variable, you can use it from any directory that a .x file lives in. I even took it home where I've only got whidbey installed ... though I had to reset the reference to the DirectX assemblies, the app compiled under .NET 2.0 without issue.
For 3D geometry authoring, Milkshape3D seems pretty good, plus it has a .x exporter so you can save your assets in usable form. I haven't worked with it very much but I'd better get on the ball. It's shareware so registering it is really cheap.
Overall, I'm really looking forward to what those boys come up with ... these are some very exciting times for programmers.