Their terminal app will simulate a selection buffer for you (although it doesn't integrate with other apps which is why I end up pasting garbage into my terminal almost every time I clone something from github) and can optionally simulate pointer style focus like many X11 window managers do.
Every text widget in Cocoa seems to use Emacs-style GNU readline shortcuts. Something I didn't notice until recently.
Xquartz isn't dead, and interestingly Xlib has outlasted quickdraw and carbon, their own drawing APIs.