Erik Arvidsson notes how the SVG 1.2 spec describes a set of tags (RCC) for creating custom elements. It's very similar to XBL (although RCC has less features -- and is less already implemented for that matter). It has an equivalent to the children tag and to some degree has the concept of anonymous content.
The spec also refers to dSVG which appears to be a limited set of UI widgets -- kind of like XForms has a limited set of UI widgets also. It also describes a pile of tags for doing scripting-like tasks without scripting (also like XForms).
The dSVG spec contains the phrase: 'Enables Web designers with no programming skills to create dynamic, interactive Web applications'. Aaaaaaaaaarrrrrrrrrrrggggggggggggghhhhhhhhhhhhh!!!!!!!!! Bzzzzt. Wrong! The last thing the world needs is more web designers with no programming skills making web applications. Have you seen the existing Web? Most of those web designers don't even understand CSS. Imagine:
Customer - how will you build our new web site?
Contractor - we are going to hire some web designers with no programming skills to build you a dynamic, interactive Web application.
Customer - and people will be able to use it?
Contractor - oh, you want a usable application? That will cost a lot more.
It's one thing to make things easier to implement. It's another to make it 'too easy'. (Note: people who don't understand programming won't understand programming even if you disguise it as XML.) In my opinion, it's better if something is more difficult to do -- you'll find that it makes for better, smarter people working on it.
Anyway, getting back on topic, there are already XUL and other similar languages for creating UI in web applications. Why not just use them, or expand on them, or use them as a starting point? Because they aren't W3C recommendations? I'm beginning to see why some people don't like the W3C.
The SVG spec also refers to some functions added to the 'window' object for loading and posting content. Huh? And this is specific to vector graphics how? Is it because the SVG working group wants to compete with Flash?
All of these things I've mentioned have one thing in common: None of them belong in a specification of a vector graphics language. I realize it's still a working draft, but it seems the authors have just given in and randomly added unrelated features, instead of creating a more robust vector graphics language.