Here's another experiment. Turn your cell phone off unless you are making a call or expecting an incoming call, and compare the time between charges with leaving it on (if you want your phone as a means of being contactable, you won't want to do this). Your phone has to regularly check in with the network to tell it where to route calls. This isn't for free. Same issue with WiFi: even if you are not accurately transmitting, the network needs to know where you are.
3/8/08 at 3:43am