Here’s an example of a directory tree they create:

2006
  2006-10
       IMG_48324.JPG
       IMG_48325.JPG
       IMG_48326.JPG
       IMG_48331.JPG
       IMG_48333.JPG
       IMG_48334.JPG
       IMG_48337.JPG
  2006-11
       IMG_48338.JPG
  ...etc...

move-digiphotos
This bash script (move-digifotos) scans EXIF tags from .JPG files in current directory with metacam, creates necessary directories under $BASEDIR and moves the files in them:

#!/bin/bash

# Reads EXIF creation date from all .JPG files in the
# current directory and moves them carefully under
#
#   $BASEDIR/YYYY/YYYY-MM/YYYY-MM-DD/
#
# ...where 'carefully' means that it does not overwrite
# differing files if they already exist and will not delete
# the original file if copying fails for some reason.
#
# It DOES overwrite identical files in the destination directory
# with the ones in current, however.
#
# This script was originally written and put into
# Public Domain by Jarno Elonen ; in June 2003.
# Feel free to do whatever you like with it.

BASEDIR=/home/backup/test

find -maxdepth 1 -name "*.JPG" | while read x; do
DATE=`exiftags "$x" | \
   egrep "^[ t]*Image Created:" | \
   sed -r "s/Image Created: ([0-9:]*).*/\1/"`
if [ ! -z "$DATE" ];
then
    YEAR=`echo $DATE | sed -r "s/([0-9]*):([0-9]*):([0-9]*)/\\1/"`
    MONTH=`echo $DATE | sed -r "s/([0-9]*):([0-9]*):([0-9]*)/\\2/"`
    if [ "$YEAR" -gt 0 ] & [ "$MONTH" -gt 0 ]
    then
    INSTDIR=${BASEDIR}/${YEAR}/${YEAR}-${MONTH}
    install -d "$INSTDIR"
    INSTFILE="$INSTDIR/$x"
    if [ -e "$INSTFILE" ] && ! cmp -s "$x" "$INSTFILE"
    then
        echo "WARNING: '$INSTFILE' exists already and is different from '$x'."
    else
        echo "Moving '$x'"
        cp -ax "$x" "$INSTFILE"
        if ! cmp -s "$x" "$INSTFILE"
        then
        echo "WARNING: copying failed somehow, will not delete original '$x'"
        else
        rm -f "$x"
        fi
    fi
    else
    echo "WARNING: '$x' doesn't contain date."
    fi
else
    echo "WARNING: '$x' doesn't contain date."
fi
done