I have a western digital mybook world.
it has timemachine support so that I can use it as a backup drive.
i run osx lion.
out of the box the mybook world doesnt support it properly though.
it does work perfectly with snow leopard.
to get the NAS to work with now lions timemachine backups you need to update the firmware.
you can update the mybook world firmware automatically, or manually.
to upgrade the firmware automatically:
to do it manually:
you can now use the mybook world as a time machine backup.