btIO bluetooth tray icon is a simple Bluetooth Mode Switcher that resides in the tray. It *should* run on Windows Mobile 5 based PocketPCs with the Microsoft Bluetooth Stack.
Copy the CAB file to your device and double click it.
The program is installed to Program FilesbtIObtIO.exe and a shortcut in the autostart folder is created.

There are three icons:

Green BT-Icon = Bluetooth is enabled and in discoverable mode
White BT-Icon = Bluetooth is enabled and in connectable (invisible) mode
Red BT-Icon = Bluetooth is disabled

You can switch between connectable and disabled by simply pressing the icon in the tray bar.
When you tap'n'hold the icon a menu apears that lets you set the mode you like, and lets you exit the program.