[nileshk]

Actually, the Cocoa (aka "nextstep") build of GNU Emacs 23.1 works exactly this way by default. Option is Meta, and various typical Mac Cmd shortcuts work by default (many of the ones that Aquamacs supports). For example:

  Cmd-C/X/V - copy/cut/paste
  Cmd-Z - undo
  Cmd-N - new frame (or "window" in Mac terminology)
  Cmd-W - close frame (if not last frame)
  Cmd-` - switch between frames
  Cmd-H - hide application
  Cmd-M - minimize frame
  Cmd-, - customize
  Cmd-K - kill buffer
  Cmd-T - bring up Mac font chooser
  Cmd-S - save
  Cmd-A - select all
  Cmd-O - bring up Mac file chooser

And of course you can define your own actions that use Cmd if you'd like.

I think, for new users, the way Emacs does frames/windows/buffers is worth discovering instead of what Aquamacs does by default.