Security leaks happen. The lesson here is treat anything that you put on a machine you don't completely control as being at-risk, even if you pay for top notch

Security leaks happen. The lesson here is treat anything that you put on a machine you don't completely control as being at-risk, even if you pay for top notch security and the vendor guarantees it. The guarantee (and any compensation) isn't a lot of comfort if the information hits the wild. This includes everything from web servers on Amazon to your Gmail account. In the case of Dropbox, I would suggest PGP or Truecrypt anything sensitive and keep the keys locally or in another location that is completely unrelated to the box.