Apple has released an update to the "Digital Camera Raw Compatibility" software to version 2.3. This update is applicable to iPhoto '08 and Aperture and adds RAW format support for Canon EOS 50D, Nikon D90, Sony A900 and compact Nikon P6000. Besides that, Apple declares that the update improve stability of RAW conversion, it's not specified to what aspect specifically.

Link to download the update is here.