I just got an email telling me that this very very old script of mine stopped working under CS5
The script automatically creates a backup copy of the current document while saving. Apply cmd-S as shortcut for the script and you won't notice it is there.
Before using the script you need to adjust three lines in the code to point to your preferred backup-location.
Currently the backupfolder is on the desktop. You could point to a deeper subfolder of the desktop by changing line 4
In case you want your backupfolder somewhere else, change the code like this
The script creates a subfolder structure. One subfolder for each day you do a save in the form yyyy mm dd and each document gets a time-prefix in the form hhmmss_