The latest (and final Tiger update) contains a boatload of benefits for Aperture users. New Raw support for over a dozen cameras, changes to Core Image that improves Spot and Patch correctness, and improved RAW file format compatibility for the Canon Digital Rebel XTi / 400D / Kiss X Digital, Nikon D80, and Pentax *ist DS. The update also tackles that pesky “lines sometimes appearing in images exported from Aperture” problem. You can read the official Apple release for complete details.
Micah pointed out to me that there’s still no support for the Leica M8, although Apple did add the Digilux 3.
I downloaded Mac OS X 10.4.9 via Software Update for both my MacBook Pro and PowerBook G4. So far, everything is running fine with no issues to report.