I've seen several posts on Lifehacker and Gizmodo about this device. Apparently, it can format hard drives for you without the use of a computer. I kind of like the idea of this, even though I think there are better ways to accomplish the task.
I know several people who put their old computers in their basements when they get a new one in the hopes that they will someday find a use for their old computers - they never do. Usually, this leads to two or three computers collecting dust until they decide to donate or dispose of them. Herein lies the problem. The average computer user will not always think to format his or her hard drives before turning over a computer.
You have a ton of personal information on your computer that still exists, even if you delete the files from your computer - the data is physically etched into your hard drive. It's essential to format or otherwise destroy your hard drive before giving it away. Since most people do not know how to do this (as it is not particularly simple to format a boot volume), this device would be perfect.
For power users, I would recommend using an IDE-to-USB converter and formatting using your operating system.