It seems like a great idea, doubling screen real estate. Imagine having widgets with your weather and Twitter feed on the lower screen, while working on a spreadsheet or more likely browsing online on the top. Mulit-monitor setups work well with desktop setups, so why not with your laptop or tablet?
Acer Iconia 6120
Featuring dual 14" displays (1366 x 768 pixels) and an innovative touch-enabled software, the Iconia has a Core i5 processor inside, 4GB of RAM, for about $1,199 retail. The only drawback is the slightly rotund 6lbs weight and the lack of a SD card reader. For a virtual keyboard, it's very easy to type and we like that you can activate the keyboard by placing both palms on the lower screen.
Toshiba Libretto W105
Even with its diminutive size, the Libretto can span a single window across both displays or display two different desktops areas on each screen, all navigable with multi-touch control. The Libretto also provides full typing ability thanks to a virtual keyboard with six modes, including Simple, Full, Thumb, and even a 10-key pad. The Libretto is powered by Windows 7 Home Premium and comes equipped with an Intel Pentium processor, 2 GB of fast DDR3 memory and a 62 GB solid state drive.
The Kyocera Echo is a smartphone with a 4.7 combined touchscreen and Android with hotspot capability. It's great that you can use one app on the two screens. One downside to all this extra screen space? Double the screen, half the battery life. There's a 1GHz Qualcomm QSD 8650 Snapdragon CPU planted inside, with 1GB ROM and 512MB of RAM. Resolution wise, the screens are 960 x 800 pixels, which adds to the bulk. But then again, that's the natural tradeoff right now when going dual screen in the mobile category.