I just wrote a Windows 7 feature focus article for Windows Gadgets. And speaking of Microsoft technologies that have never taken off in any meaningful way, we also have this...
Windows SideShow for Windows Mobile Developer Preview
Brief Description
Windows SideShow for Windows Mobile is an application for Windows Mobile 5 and 6 PocketPCs and Smartphones that allows you to use your Windows Mobile device as a Bluetooth SideShow device. Installation instructions are below. This is a beta release.
Overview
Windows SideShow for Windows Mobile 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 an English-only release.