"Everywhere" means the kind of ubiquity that the Flash player enjoys on Windows and Mac desktops, and to a lesser extent on Unix and handheld devices. And it sets up an arms race between Adobe and Microsoft, each giving away razors (that is, players) in order to sell blades (development tools).

Here's a crazy idea: Open-source the WPF/E, endorse a Mono-based version, and make XAML an open standard. Why? Because an Adobe/Microsoft arms race ignores the real competition: Web 2.0, and the service infrastructure that supports it.

The HTML/JavaScript browser has been shown to be capable of tricks once thought impossible. Meanwhile, though, we're moving inexorably toward so-called RIAs (rich Internet applications) that are defined, at least in part, by such declarative XML languages as Adobe's MXML, Microsoft's XAML, Mozilla's XUL (XML User Interface Language), and a flock of other variations on the theme.

Imagine a world in which browsers are ubiquitous, yet balkanized by incompatible versions of HTML. That's just where RIA players and their XML languages are taking us. Is there an alternative? Sure. Open XAML. There's a stake in the ground that future historians could not forget.