Apple could imitate a fair bit too. For instance, I'd like the OS X 10.6 Finder to be as useable as the Nautilus file manager that shipped with Ubuntu's Gnome 2 in 2010.
The version of Nautilus shipping with GNOME 3 is obviously very heavily inspired by this version of Finder.
The only thing I find myself missing is a way to move up the file-structure without having to switch to the list-view when you've opened a folder without actually navigating your way to it through Finder. Essentially, the "Back"-arrow would take you to the parent folder even if you didn't navigate from it.
Isn't that just Cmd+Up?
Oh the glorious day when I found out about this..