I have to respectfully disagree with Marc Clifton's article on Code Project. There is one definition of what "XAML" is - it is a set of technology that Microsoft is producing. Whether or not we license it to other vendors, people attempt to clone it, or what, there is still only one thing that is XAML. I feel somewhat passionately as I, and other people I work with, invented the thing and are still working on the final definition of it.

If you want to claim that Xamlon, MyXaml, and other attempts at XAML clones are in fact XAML, that is incorrect. They are attempts to clone XAML.

If you article was entitled "what are options in declarative UI definition" and you listed "XAML and Avalon", "Xamlon and Windows Forms/VG", "Lazlo", etc., I would have no complaint. MyXAML is not XAML, Marc even says this himself. Lazlo is clearly not XAML. I don't have anything specifically against MyXAML, Xamlon, Lazlo, Flex, XUL, or any other declarative UI programming models - but I would no sooner claim that XAML was Flex as I would expect Macromedia to claim that Flex was XAML.