Yesterday, the Windows Embedded team released support for Windows SideShow on Windows CE 5.0! Combined with our Universal Driver, this new platform can work over USB, Bluetooth or TCP/IP connections, and easily enable SideShow functionality on a wide variety of CE-based devices. If you've got an existing CE 5 based device with one of the supported transports, adding SideShow support in most cases won't require any additional hardware.
It's also a standard part of Windows Embedded NavReady 2009, a SKU designed specifically for navigation devices. With SideShow, now your PND could be as useful outside the car as it is inside--imagine using it as a remote control for your music library at home, or even a PowerPoint remote (with full slide previews and speaker notes) once you've gotten to your destination? The possibilities are endless, and now they're easy to implement as well!
All you need to get started is Platform Builder 5.0--so what are you waiting for?