Yesterday, during a meeting with a local business group, we started talking about data backup, and one of the attendees mentioned she's using Dropbox to backup the book manuscript she's been working on for a year. While Dropbox is THE hot new Internet start-up (check out the recent article in Forbes), and it's a beautifully simple tool for collaboration and mobility, I cringed at the thought of relying on this service to protect a years worth of work. I strongly suggested that she set up a secondary backup for her work, and also mentioned to the rest of the group to check into security and privacy concerns.
Last year there was a serious security breach at DropBox during which for several hours, any user could access any account with any password. If you're not very concerned about the privacy of your documents, this in itself may not scare you away, but it opens up the door of where else there might be deficiencies.
In Ed Bott's blog post today on ZDNet - Sorry Dropbox, I still don't trust you, he highlights several other concerns. Last year he canceled his account after the security breach, and then recently opened a new account to collaborate with co-workers. After being alarmed when he received a referral thank you from someone he didn't know, he questioned again whether a full security audit was ever performed.
Bottom line, Dropbox is an outstanding tool for mobility between your computer, laptop, smartphone and tablet, and it's an outstanding collaboration tool, but think twice before using it for confidential documents, and don't use it as a primary backup of your work.