Rob Sobers writing about a statement Marco Arment made on his podcast about Dropbox:
Marco’s response echoes my personal feelings about Dropbox and other public cloud services – treat Dropbox as though it’s nearly public. Marco’s rule of thumb is that he doesn’t put anything in Dropbox that could potentially be harmful or embarrassing if it were leaked.
Regular readers will know that I am paranoid about this kind of data breach. So my solution? Sensitive stuff goes inside an encrypted DMG inside of Dropbox. I am willing to trade a bit of security for the ease of use Dropbox offers.
Also remember that there is a Dropbox like solution that is encrypted on the user end, called: SpiderOak.
Or your can use this tool to encrypt first (never tried it).