This was a cool little application that seems to have flown under the radar. If you have a Vista laptop and a Windows Mobile Smartphone and both they are paired via BlueTooth then this is for you. The install is Sideshow for mobile and after you install the Office PowerPoint gadget you can control your PPT from your phone as well as see your speaker notes on the phone.
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.
Windows SideShow for Windows Mobile Developer Preview
Use a Windows SideShow-compatible device to remotely control PowerPoint presentations on your computer. You can move forward and back, or jump to a specific slide in the presentation. You can also preview the next slide and view slide notes on the device.
Office PowerPoint Remote
Installation is pretty straight forward, just follow the installation doc and you should be good to go.