Hiding emacs backup files in Finder
If you don't like all the #*# and *~ files floating around in your working directory, put the following elisp code in your .emacs file.

;; Put autosave files (ie #foo#) and backup files (ie foo~) in ~/.emacs-backups/.
(custom-set-variables
  '(auto-save-file-name-transforms '((".*" "~/.emacs-backups/autosaves/\\1" t)))
  '(backup-directory-alist '((".*" . "~/.emacs-backups/backups/"))))

;; create the autosave dir if necessary, since emacs won't.
(make-directory "~/.emacs-backups/autosaves/" t)


Reference: http://snarfed.org/gnu_emacs_backup_files