Bluetooth is a short distance wireless protocol used as a "cable replacement". It is based on a series of subprotocols to support both data and voice transmission between two devices such as a cell phone and a headset. For data services it can be used the same as a serial cable to connect two devices such as a cell phone and a GPS the same way a cable would.
It uses the 2.4 GHz spectrum and does not require a FCC license to use.
Windows Mobile Pocket PC
devices are available from all carriers that support Bluetooth.