Jeff,
Glad to hear you had a good crop in the EarthTainers this year!
Regarding end of Season maintenance, it depends on your storage options. If you can store the Potting Mix, I would empty them out and clean out errant roots, etc. alternatively, (if you have the EarthTainer III removable cages), you can put the 'Tainers in a large black trash bag for the Winter, and store them outside.
If you have the older version EarthTainer II with the fixed cage, then try to wrap as much of the exposed container in plastic trash bags to prevent UV from the Sun, which would damage the container material.
Anyway, start planning your seed varieties for 2012 in the cold months ahead.
Raybo