The slider form-factor isn't unusual in mobile devices - HTC's Touch Pro2 has a particularly nifty mechanism, and larger handhelds, such as the PsiXpda UMPC, have used it too - but how about a 10.2-inch slider tablet? That's what InsanelyWind forum member c0ff33 is working on, turning his Advent 4211c (a rebadge of the MSI Wind U100) into a touchscreen tablet that opens up to reveal the QWERTY keyboard.
Right now he's managed to flip the display around and fit the touchscreen layer, as well as add some custom shortcut buttons that allow him to more easily choose between the dual-booting Windows 7 or OS X 10.6.2 installs. Unfortunately there's no sign of the sliding mechanism as yet, but it's working as a regular slate instead.
c0ff33 has extended the LCD connectors in preparation, and is now looking for suitable sliding hinges. We're not entirely convinced this is the ideal form-factor for a device of this size - especially considering how far up the touchscreen will have to slide in order to reveal the keyboard - but we'll withhold judgement until the final results.