Maybe you've seen the notebook with Windows SideShow at Developer & IT Pro Days in Belgium last month. If not (or you don't know what it is), MSDN Library explains the Windows SideShow platform as follows:
The Microsoft Windows SideShow Platform is a new feature developed for Microsoft Windows Vista that enables developers to create new and extend existing applications specifically for devices with small displays and limited interaction models. Applications designed to work with the platform are referred to as gadgets. The devices supported by the platform include, but are not limited to, displays attached to a laptop, front panel computer displays, displays embedded in keyboards, cell phones, digital picture frames, and other display devices.
You can now download a simulator for Windows SideShow, so that you can build and test your SideShow gadgets without having the physical hardware. The emulator looks like this: