Jon Udell suggests that the true synthesis of the Unix pipe model and the richness of GUIs lies in using XML instead of simple text input/output. I believe this is a very interesting idea, although clearly, just replacing tool-specific text output with XML output that is just as tool-specific will not buy you a lot. You would be able to use an XML editor, just as you can use a text editor to look at the output of a grep command; this will not make dealing with complicated outputs easier — after all, XML only streamlines syntax, not semantics. I’m not really sure I see the solution in XUL or XAML. Both use XML, true — but that doesn’t mean they make dealing with XML data easier (they might, but I don’t see how they would be more suited to this just because they use XML to specifiy UI layout; these are orthogonal concepts). Maybe the semantic web/RDF vision is not so academic, after all …