Bluetooth heats up my mb with 10 degrees.
When Bluetooth is enabled, my macbook gets around 8 Celcius degrees warmer. Wifi is enabled, one window open and surfing (ClickToFlash enabled) and my mb is around 49-51 degrees. When I turn on bluetooth, mb gets around 58-60 degrees.
iMac 2.66 GHz, NVidia 9400, Mac OS X (10.6.2), 4GB DDR3 SDRAM
