Monitors that connect via USB aren't new, but Century Japan's is sufficiently different to be interesting by virtue of the fact that it's a mere 4.3-inches. Intended to accommodate your instant messenger program, system stats, media player or PhotoShop toolbox, the WVGA 800 x 480 display has an adjustable kick-stand and is bus-powered so requires no external PSU.
Up to seven will apparently work off of one PC or (Intel-based) Mac. It uses an LED backlight and the brightness is rated at 200 cd/m3. It ships in Japan in mid-November.
The big drawback is the price: ¥19,800, which works out to around $199. For that you can pick up a new 19-inch LCD monitor and still have change left over. Of course, the people who like the idea of the smaller screen probably have different intentions for it that a much larger one wouldn't be suited to, but for that money it's likely to stay pretty niche.