Recently, some people have been bugging me to get external linking working. It seems that they want to use librsvg + SVG templates in the pre-press business (which would have never been possible without the hotness that is Cairo, I might add).
To help these folks out (and make a few quick $$ while I'm at it), I've cooked up basic support for the xml-stylesheet standard, external entities and the CSS @import statement. Next on my list is to support a subset of the XInclude standard, and things should be peachy. I'm sure that I screwed up somewhere, so I'd appreciate if people would try this out and let me know what breaks.
For the icon theme authors in the audience, this means that the next version of GNOME will support the same sort of templating features that those pre-press guys wanted. You'll be able to share stylesheets between icons and be able to share SVG snippets between icons (eg. include the same SVG code that draws the "document" in all of your mime-type icons). This should hopefully make it easier to create, modify and parameterize your icon themes. Enjoy!