Exif to date is a simple Nautilus script that takes a bunch of images and resets their modification date to the one corresponding to the EXIF tag.
If you're a Debian/Ubuntu user, just install the package (then enable the script with System → Preferences → Nautilus Scripts Manager).
Otherwise, download the script above to /home/yourusername/.gnome2/nautilus-scripts and make it executable.
When I wrote exif-to-date, I ignored that the program jhead, present in Debian/Ubuntu repositories, allows one to do the same thing (compared to exif-to-date, it only lacks a graphic interface) by just giving the command:
jhead -ft *.jpg
and the opposite (assuming pictures already have an EXIF header, otherwise add option “-mkexif”) with
jhead -dsft *.jpg