Update:
I have found that the line:
> svgS = cairo.SVGSurface("thingum.repo/cube.svg",400,400)
Actually *writes* to the filename and erases it. I don't know if this is
expected behaviour, but it leaves me wondering how to get an SVG file *into*
a Source.
I'm looking for a pyCairo mailing list right now.
\d