Depends on the class of bluetooth. Class 2 has a maximum permitted transmission power of 2.5mW. Class 1 is 100mW. Either way, it's a lot less than the 3G radio's power. But that makes sense...bluetooth is generally talking to something in the same room...3G is talking to a tower hundreds of meters (or more) away. http://en.wikipedia.org/wiki/Bluetooth And has been noted...these numbers reflect the amount of power being radiated by the antenna...the underlying chip logic generating the signals consume energy in addition to that.
I don't remember where I read it, but ~2mW was the difference in the consumption if the BT was simply on instead of off and if receiving-transmitting should be ~1W. Could be really wrong though. In any case, 2.5mW doesn't look like a realistic number for something transmitting/receiving. .
Of course, bluetooth takes 2.5mW (times two for both sides of the connection), while HSDPA takes 2W, so there is much more HSDPA pain than bluetooth gain.