Windows SideShow is a technology in Windows Vista that supports a secondary screen for your Vista PC or laptop.  With this additional display, you can view important information whether your laptop is on, off, or in sleep mode. Windows SideShow uses gadgets, and convenient mini-programs, to extend information from your computer to other devices. Gadgets can run on a Windows SideShow–compatible device and update that device with information from your computer.

Unfortunately, SideShow has not attracted as much development as it could have due to the chicken-or-egg problem. With only a few SideShow devices available, not many gadgets have been made, and with few gadgets, there has not been too much incentive to buy a SideShow device. This is, however, soon set to change with the preview release of Windows SideShow for Windows Mobile. Any Windows Mobile 5 or 6 phone can now work as a Bluetooth Windows SideShow device. These connected phones may be used to control PowerPoint presentations while viewing the speaker notes, as a remote control to Windows Media Player, or viewing RSS feeds on the road, or many other functions, only limited by the gadget developers. With an installed base of 35 million Windows Mobile phones, the Sideshow market has just been blown wide open, and this will be followed by much-increased developer support.