Along with Mac OS X 10.5.3, Apple also sent out Digital Camera RAW Support Update v2.1 which extends RAW file support for Aperture 2 and iPhoto '08 to the following cameras:
Canon EOS Digital Rebel XSi/Kiss Digital x2/450D
Epson R-D1
Leaf AFi 7
Leaf AFi 6
Leaf AFi 5
Pentax K200D
Pentax K20D
Enjoy, Alex.