Finally! With Apple’s OS X 10.4.9 update, Pentax K10D users can view K10D .PEFs natively in OS X Preview, and also in Aperture, and PEF converted DNGs will also be displayed properly now (Aperture only shows DNGs properly if the OS itself has a RAW converter for your RAW format).

Now I can properly evaluate Apple Aperture versus Adobe Lightroom, for my K10D RAW files.

K10D support in Aperture, for 10.4.9 OS X 10.4.9 download