Hmm. The behavior I describe above was what I consistently found under OS 10.4.x, and I assumed it would also be true of 10.5. Wrong assumption. Behavior under OS 10.5 seems to be different when you drag some items out of System/Library/CoreServices/Finder.app/Contents/Resources--documents you drag out, will get moved to the destination, removing it from the Resources folder, and the file's permissions don't get changed. Maybe Apple changed the behavior in 10.5 to accommodate people dragging modified default_smart.plist files into the Finder's Resources folder? But dragging folders out of Resources, or items inside folders that are inside of Resources, copies them to the desination, leaving the original in Resources. Go figure.

That's what I noticed, so I didn't mention it in the hint. IIRC, I didn't muck with the permissions on my changed plist in Tiger, either.