This is kind of a unique design. The i620 smartphone from Samsung is a slider, but is a slider in the more traditional, non-smartphone sense. Windows Mobile runs this beast and it also includes Wi-Fi, 2-megapixel camera, Bluetooth, MicroSD expandability and more. Under the slider is a full size keyboard and actually I am kind of intrigued by this design. I've always been a sucker for a sweet slider, though.
Samsung i620 Slider Smartphone [CrunchGear]