In addition to the mac-specific ways, if you set your Terminal app to Fullscreen (the double diagonal arrows on the top right of Lion+), you can just invoke ema

In addition to the mac-specific ways, if you set your Terminal app to Fullscreen (the double diagonal arrows on the top right of Lion+), you can just invoke emacs from the command line. I did this while evaluating whether emacs+evil was something I'd be interested in and it worked just fine. To be honest, I spend most of my time using OSX in a single fullscreen Terminal.app inside tmux.