Apple yesterday posted new installers for the Digital Camera RAW Support Update first released earlier this month. Now at v1.0.1, the description of what's new is unchanged. Namely, the update adds support to Aperture, iPhoto and Preview for RAW files from the Canon EOS Digital Rebel XTi/400D, Nikon D80 and Pentax *ist DS, plus fixes several bugs. Presumably, Apple discovered an error in the first iteration of this update or its installer, fixed the problem and has now re-issued the update (the original update has been pulled from Apple's site).
Digital Camera Raw Support Update v1.0.1 is available in separate PowerPC and Universal Binary installers. Mac OS X 10.4.8 is required.