Here is the repo: https://bitbucket.org/mituharu/emacs-mac
Skimming the readme, I see that it's almost entirely mac specific and mostly UX. I can't say they are completely useless but nothing really vital, except the features inherited from Carbon, which seem useful (I really like the concept of AppleScript, i.e. all programs responding to a single programming interface; I guess DBus is supposed to do sth. similar on FreeDesktop, no?).