It's sorta weird how Apple didn't completely port Carbon to 64-bit, but the Finder is written in Carbon. Want proof? /System/Library/CoreServices/Finder.app/Contents/Resources/English.lproj/AboutWindow.nib
If you open the inspector, you'll see various Carbon-only things, like Controls, Commands, 4chr, etc. And most of the library things are HI*.
Note: you need the Developer Tools to view nib files