This looks like it might be interesting:
http://xmlgraphics.apache.org/fop/Sounds like it's able to take input from SVG and produce PDF.
If anyone's interested in svg2pdf, this might be worth experimenting with to see if it's any good. It's available under the Apache license.
FOP uses batik (http://xml.apache.org/batik/) to perform its svg-to-pdf "transcoding", as they call it. The output is pretty impressive for many situations, but alas:
1. It's written in java, and doesn't yet compile/run using gcj (although they're close) 2. it's a bit slow, and still occasionally vomits all over your svg
What this does potentially give you, however, is a way of getting transparency into PDFs: PDF1.4+ supports actual transparency, whereas PS-level 3 and friends do not (I believe the current inkscape svg->pdf mode has an (e)ps intermediate step).
Do people feel inkscape should natively output PDF? ...Eric