Comment 2 for bug 664335

tested on OS X 10.5.8:
Not reproduced when using Inkscape 0.48+devel with cairo 1.8.10 (exports to PDF 1.4)
Reproduced when using Inkscape 0.48+devel with cairo 1.10.0 (exports to PDF 1.5)

There have been no changes in Inkscape with regard to PDF export: it seems that the most recent (stable) cairo version uses PDF 1.5 as default.