Windows Sideshow is now avaliable for Windows Mobile 5.0 and 6 devices. This release is only a Beta and intended for Developers. However if you wish to try some of the great features like controlling Windows Media Player or Powerpoint from your device via Bluetooth, I advise you to download this small application here.
There few are steps you must take:
Install the CAB file on your device;
Create a Bluetooth partnership from your PC (Microsoft BT drivers recomended);
On the device properties go to bluetooth services select Windows Sideshow;
If prompted to install a driver get the files here;
Finaly go to your control panel – Windows Sideshow and activate the gadgets you wish;
The Powerpoint gadget is not avaliable by default so I recomend downloading it from here.
You will need Windows Vista 32 or 64 Bit edition. Developers might want to take a look here