I am in the process of moving most of my work with photos to Aperture from iPhoto. I have been working with referenced files in Aperture with the master files staying in iPhoto. How can I move the master files to Aperture without de-stabilizing iPhoto?

You can do this very easily using Aperture's Consolidate command. Select the images and go to File > Consolidate Master... or for an entire project control click on the project and choose Consolidate Masters for Project...:

While consolidating usually moves the master files into the Aperture library (so causing iPhoto grief), there is an option to copy the files instead. This leaves the originals intact:

Of course now you have two masters on your disk, one in iPhoto and one in Aperture. Once you have confirmed that Aperture has the photos in its library as expected, you can delete the iPhoto copies.

Tags: Aperture, Q&A, iPhoto, Referenced, Consolidate