I know, the Foleo is spelled with an "e" ... Either way, it's such a silly proposition only Steve Jobs could hype this thing enough that people might buy it. And if he did, the only benefit would be keeping the computer gene pool diverse by preventing people from buying a decently spec'd Windows laptop, for about the same price.
The interesting bit is that we do need optional larger displays for small computing devices so that we can get the most out of them as they continue to increase in power and connectivity. So what would work better than this non-laptop?
I worked with Tim Andrews at Viant in "Web 1.0" and one time he took us out of our way to look at the latest video goggles from Sony Japan. Ok, personal movies ... huh? I didn't get it. The goggles are going to be the video output for this, Tim explained, pointing at his Palm. Tim has spent much of his career thinking ahead, and this time was no exception. The 1999-era Palm would've taken 30 seconds to BlT a frame for these goggles. But now?
Let's see... Modern smartphone hardware can drive a VGA display or larger. And here are the visor displays: VGA for about $400, and SVGA for $1600. Like most hardware, the price is inverse-exponential with volume. That's a fancy way of saying these are expensive gadgets 'cause no one makes a lot of them. The price will drop drastically as they are produced in higher volume.
On the input side, there are old fashioned Bluetooth or more futuristic solutions and bear in mind: you don't always need big input and big output at the same time. Web browsing and document review can benefit from a big screen, but hardly need a full-sized keyboard. So there's no reason to fill your lap with another battery-chewing, airport-security-antagonizing monstrosity just to follow up on some links.
Small computing devices are about mobility and convenience. They are hardly "enhanced" by chaining them to a big dumb anchor. But the tech is here to take a smartphone-grade device and get a ton more productivity and value out of it by widening its human I/O bandwidth with these virtual keyboards and virtual big screens.