According to a post on the Consumerist blog, they setup a sting and caught a Geek Squad technician stealing media files from a computer that was in their shop for some service.
The Geek Squad was hired to install iTunes on the sting computer, however the video shows the technician allegedly copying media files, including pictures, from the computer and pasting them to a USB thumbdrive.
This is not an indictment of Geek Squad. I am certain that behavior like this is not approved by Geek Squad and I am sure that they will investigate and take the appropriate action.
However, anytime one takes their computer to a relative stranger and gives them unbridled access, that individual runs the risk of this type of thing happening. It does not mean that one is at risk for this type of thing only from the Geek Squad. The end of the video gives good advice:
By the time your computer breaks, its too late to hide your stuff from potential voyeurs. So, if you have things you don’t want people looking at, lock it down.
This could just as easily happen with financial data or other personal information, like e-mail, that you have stored on your computer. The “lock it down” mentioned above means “encrypt your data”.