I am going to use 'rsnapshot' to create backups of my local & remote computers. My intension is that I can use these backups to restore disk images when needed -> install Linux from scratch and then copy the subdirectories from 'rsnapshot' backup to the new Linux installation.
My question is ... what subdirectories should be excluded in the backup. Now I have following excluded ... but are they the right ones or have I missed something:

exclude /proc
exclude /lost+found
exclude /mnt
exclude /media
exclude /sys
exclude /home/lost+found
exclude /tmp

It depends on where you keep things - you can ignore /dev and possibly /lib, /lib64, /selinux. Assuming you only install things via package it may be quicker to list want you want - /etc, /home, /var/www etc

Another thought - you may break your package management and/or packages if you restore any of the system binaries over the top

Some strange things happened with my 'rsnapshot'.
My config-file looks like follows:

$ cat /etc/rsnapshot_zkab.conf
# Config för ZKAB

config_version 1.2
snapshot_root /rsnapshot_backups/zkab/

cmd_cp /bin/cp
cmd_rm /bin/rm
cmd_rsync /usr/bin/rsync
cmd_ssh /usr/bin/ssh
cmd_logger /usr/bin/logger
cmd_du /usr/bin/du
cmd_rsnapshot_diff /usr/bin/rsnapshot-diff

linux_lvm_cmd_lvcreate /sbin/lvcreate
linux_lvm_cmd_lvremove /sbin/lvremove
linux_lvm_cmd_mount /bin/mount
linux_lvm_cmd_umount /bin/umount

retain hourly 3
verbose 2
loglevel 3
logfile /var/log/rsnapshot.log
lockfile /var/run/rsnapshot.pid

exclude /rsnapshot_backups
exclude /proc
exclude /lost+found
exclude /mnt
exclude /nfs
exclude /cifs
exclude /media
exclude /sys
exclude /dev
exclude /tmp

exclude /home/lost+found
exclude /home/raivo/bittorrent
exclude /home/raivo/Downloads/Liaison
exclude /home/raivo/movie
exclude /home/raivo/Music
exclude /home/raivo/Pictures
exclude /home/raivo/tmp
exclude /home/raivo/Video_Projects
exclude /home/raivo/Videos
exclude /home/raivo/.cache
exclude /home/raivo/.VirtualBox
exclude /home/raivo/.gvfs

link_dest 1
one_fs 1

backup / localhost/
-------------------------------------------------------------------
For some reason /boot, /home and /selinux are empty in the backup folders ... why ... my logfile looks OK:

[13/Jan/2011:16:47:18] /usr/bin/rsnapshot -c /etc/rsnapshot_zkab.conf hourly: started
[13/Jan/2011:16:47:18] echo 22589 > /var/run/rsnapshot.pid
[13/Jan/2011:16:47:18] /bin/rm -rf /rsnapshot_backups/zkab/hourly.2/
[13/Jan/2011:16:47:18] mv /rsnapshot_backups/zkab/hourly.1/ /rsnapshot_backups/zkab/hourly.2/
[13/Jan/2011:16:47:18] mv /rsnapshot_backups/zkab/hourly.0/ /rsnapshot_backups/zkab/hourly.1/
[13/Jan/2011:16:47:18] mkdir -m 0755 -p /rsnapshot_backups/zkab/hourly.0/
[13/Jan/2011:16:47:18] /usr/bin/rsync -ax --delete --numeric-ids --relative --delete-excluded --exclude=/rsnapshot_backups --exclude=/proc --exclude=/lost+found --exclude=/mnt --exclude=/nfs --exclude=/cifs --exclude=/media --exclude=/sys --exclude=/dev --exclude=/tmp --exclude=/home/lost+found --exclude=/home/raivo/bittorrent --exclude=/home/raivo/Downloads/Liaison --exclude=/home/raivo/movie --exclude=/home/raivo/Music --exclude=/home/raivo/Pictures --exclude=/home/raivo/tmp --exclude=/home/raivo/Video_Projects --exclude=/home/raivo/Videos --exclude=/home/raivo/.cache --exclude=/home/raivo/.VirtualBox --exclude=/home/raivo/.gvfs --exclude=rsnapshot_backups/zkab --link-dest=/rsnapshot_backups/zkab/hourly.1/localhost/ /. /rsnapshot_backups/zkab/hourly.0/localhost/
[13/Jan/2011:16:54:39] touch /rsnapshot_backups/zkab/hourly.0/
[13/Jan/2011:16:54:39] rm -f /var/run/rsnapshot.pid
[13/Jan/2011:16:54:39] /usr/bin/rsnapshot -c /etc/rsnapshot_zkab.conf hourly: completed successfully

Just a guess: You have enabled the one_fs option, which means that rsync does not backup mount points.

Do you have other filesystems mounted at /home, /boot and /selinux ?

I removed 'one_fs 1' and then got it OK