"Finally, after some 3rd party developers released some Windows Mobile compatible SideShow drivers, also Microsoft gives SideShow some love by releasing Windows SideShow for Windows Mobile. Not yet mass-market ready, Microsoft's Windows SideShow for Windows Mobile Developer Preview v0.01 is an application for Windows Mobile 5 and Windows Mobile 6 Pocket PCs and Smartphones that allows you to use your Windows Mobile device as a Bluetooth SideShow-compatible device. This enables you to use your phone as an extra window into your PC. You can both access your computer's information from your Pocket PC or Smartphone, and control the computer through a gadget interface.
While the phone is out of range, or when your computer is off, you can continue to view content sent to the phone previously. This makes it easy to send information to the phone that you'll need later on.
The developer preview is available in English only and supports Windows Server 2008, Windows Vista Business, Windows Vista Enterprise, Windows Vista Home Premium and Windows Vista Ultimate Bluetooth-enabled PCs using Microsoft's Bluetooth stack. Toshiba Bluetooth stack isn't supported at the moment. Furthermore, Windonws SideShow for Windows Mobile requires a Bluetooth-capable Windows Mobile 5, Windows Mobile 6 Standard or Windows Mobile 6 Professional device with the .NET Compact Framework 2.0 installed."
This is very good news and I hope the Windows Media Center SideShow gadget that has been in internal beta at Microsoft is released soon to the public. Hopefully this will be a cool way to control your media center from your hand held Windows Mobile device!
Windows Side Show team blog