I'm assuming you are using Aperture's "Edit with..." menu items. What happens in Aperture when you use an external editor like PS or OnOne, is that it creates a new version of the image to be edited as either a TIFF or PSD file and creates a new corresponding master file in that format. The TIFF/PSD is specified in the Export panel in Aperture's Preferences. (Even if you specify something stupid like Calendar for your external editor, you still have only those two choices for the format of the file to be edited.) The external edits are performed on the new TIFF or PSD version, and your original RAW is untouched. Your external edits show up in the new version when you return to Aperture.
For compatibility with Sam's and most other places that provide prints, you will have to export your edited version from Aperture as a JPEG and send out the exported file.