No, wait. It can't possibly be as simple as making the single rsync command -- which I know works from the Terminal -- the thing that the cron job does. Or can it?
Very pleased that I managed to create an rsync command that backs up the whole of my wp-content folder to my local Dropbox, which then takes care of the rest.
Now, how do I turn that into a script that cron can work with?
@hybotics Well, sort of. But I actually made an effort not to think about how or why they did things and just experience them as they came.