backups-mode

The purpose of these commands and this new major mode is to loosely approximate the autosave-with-versions API
 recently instituted by Apple for Mac OS X Lion.

Installation
 git clone git@github.com:chadbraunduin/backups-mode.git
 cd backups-mode
 # copy to your emacs load-path
 cp backups-mode.el bm-utilities.el backup-walker.el ~/.emacs.d/
 # this assumes ~/.emacs.d/ is in your emacs load-path
 # add the following to .emacs
 (require 'backups-mode)
 (backups-minor-mode)

Addtional Configuration
  putting this in your .emacs will allow you to change version control settings. These are the default settings found in backups-mode.el.
  (setq backup-by-copying t
   delete-old-versions t
   kept-new-versions 6
   kept-old-versions 2
   version-control t)
  Documentation on these settings can be found here: http://www.gnu.org/software/emacs/elisp/html_node/Numbered-Backups.html

My Personal Configuration
  As an example, here's the configuration from my .emacs file
  (require 'backups-mode)
  (defvar backup-directory "~/.emacs-backups/backups/")
  (defvar tramp-backup-directory "~/.emacs-backups/tramp-backups/")
  (backups-minor-mode)
  keep all versions forever
  (setq delete-old-versions 1)

Usage
 While editing a file-based buffer there are two new commands and some changes to note.
 Now, whenever you kill a buffer or kill emacs, all file-based buffers will be saved without prompting.
 New Commands while editing a file:
   save-version (\C-cv) will backup the previously saved version of the file.
   list-backups (\C-cb) will open a backups-mode buffer.
 The backups-mode buffer will list all backups Emacs has created for the file and will allow you these options:
   view-backup (<enter>) will open a backup file read-only.
   revert-backup (R) will backup the current file then replace the current file with the backup you've chosen.
   diff 2 files (d + d) You can choose from the current file or any backup files and diff two of them.
   purge backups (p [+ p] + x) You can delete backups in a batch fashion by marking backups then executing a deletion of all the marked backups.