SVG font support will be truly awesome. I'm very happy that someone has taken interest in this portion of the spec. I'm not particularly familiar with it yet since Inkscape doesn't support it so I don't know what to suggest. I'll forward to you off list one email of a short conversation I had with Richard Hughes about SVG fonts.
Did I? /me rummages through outbox. Oh yeah.
I reckon it would be really nice to use Cairo's user font API to implement SVG fonts, so that we get good PDF output and suchlike for free. There are just two minor problems with this plan:
1) Cairo doesn't have a user font API yet. It's due in November. (http://cairographics.org/roadmap/)
2) Inkscape doesn't use enough of Cairo yet for this to be just a simple plug-in job.
Since the API doesn't exist I have no idea what we would gain from using Cairo rather than going it alone, however I strongly recommend that you hook up with some of their people to talk about it. Get an update on the status of the roadmap too while you're at it.
Richard.