The iPhone has more antennas than an ant colony: one for the cellular network, one for Wi-Fi hot spots, and a third for Bluetooth.
Bluetooth is a short-range wireless cable elimination technology. It's designed to untether you from equipment that would ordinarily require a cord. Bluetooth crops up in computers (print from a laptop to a Bluetooth printer), in game consoles (like Sony's wireless PlayStation controller), and above all, in cellphones.
There are all kinds of things Bluetooth can do in cellphones, like transmitting cameraphone photos to computers, wirelessly syncing your address book from a computer, or letting the phone in your pocket serve as a wireless Internet antenna for your laptop. But the iPhone can do only one Bluetooth thing: hands-free calling.
To be precise, it works with those tiny wireless Bluetooth earpieces, of the sort you see clipped to tech-savvy people's ears in public, as well as with cars with built-in Bluetooth phone systems. If your car has one of these "car kits" (Acura, Prius, and many other models include them), you hear the other person's voice through your stereo speakers, and there's a microphone built into your steering wheel or rear-view mirror. You keep your hands on the wheel the whole time.
So far, Bluetooth hands-free systems have been embraced primarily by the world's geeks for one simple reason: It's way too complicated to pair the earpiece (or car) with the phone.
So what's ...