Is it possible to convert Xaml into a .Net Compact Framework UI (dll, exe, etc...)? In fact any XML based representation would be nice (QT, GTK, etc...).
XAML is currently used in both WPF and Silverlight application types to layout the screen. You can convert the XAML in to a static JPEG or Tiff however this is not much use for a real application.
They are however developing silverlight for mobiles based on silverlight 2 which should be released late 2009 allowing you to create XAML layouts and display on Nokia S60 and Windows Mobile. The downside is that the user would have to install the silverlight plugin (but not need the compact framework) and the applications scope would have limitations.
As for WPF, there are no projects that I know of to update the compact framework to support WPF. I guess this is because the .Net Compact Framework is intended to be as small as possible.
Please take a look at following Code Project article. You will be able to use MyXaml on .NET Compact Framework.