One of my early posts talked about doing backups of the RPi SD card. At least part of that post was crap so I thought I would revisit with an explanation of what I am doing now which is simply to use dd.
I take my backups of both partitions of the SD card using the inverse of the restore commands shown below.
A restore is then done to an SD card formatted to the same specifications as the backup (assuming it is not the original).
For SD cards that I use for testing I am using 4gb cards as they backup and restore faster. I might get some 2gb cards for that matter!
sudo dd bs=4M if=2013-08-03-base-image-1.img of=/dev/sdc1
sudo dd bs=4M if=2013-08-03-base-image-2.img of=/dev/sdc2