Go to www.apple.com/aperture/raw/cameras.html
for a listing of supported cameras
No digital backs are mentioned,specifically,but Aperture is compatible with the .DNG
format (provided it is converted via the Adobe converter and not captured,or created,
natively from within a DB's dedicated software).
James Russel,and others on this site,have mentioned processing Leaf and Phase One files
in Lightroom but i don't recall if they were processing the files in their DB's native raw format
or were working with DNG files