I came across a New York Times article the other day titled "If Your Hard Drive Could Testify..." It talked about how the law is ambiguous as to the nature of the computer, whether it is a container like a box, or whether it is an extension of our body, like how the brain "stores" memories. The difference is that a container can be freely searched by authorities at the border (for illegal firearms, drugs, etc.), while bodily invasions require a "reasonable suspicion".
The implications of such a definition is broad. If a computer can be freely searched at the border, then "border authorities could systematically collect all of the information contained on every laptop computer, BlackBerry and other electronic device carried across our national borders by every traveler, American or foreign."
More so than privacy issues, it was the technological capabilities of the scanner which I was more curious about. When I read the NYTimes article, I had immediately wondered if the traveler had been using Windows, which surely the scanners would work on, or at the very least the border authorities could operate. Macs are becoming more popular, too, so they might work. I use Linux, which natively runs on ext2/ext3 filesystems. Somehow I don't think the scanner would work on that. And then the incident I found mentioned encrypted drives...
I wish I was there to see the customs officer's face. It would also be fun to see the computer start, only for her to be dropped into a command line login shell. "Oh, it doesn't work on... er, Linux, right?"