Think on Bluetooth as a short-range (very short 20m approx) generic radio link that other devices can connect to. This can include (for instance) laptops using your mobile as a modem, without the need to fish it out and point it at the IR port. It can also be used to manage the phone with a Bluetooth-enabled PC and swap data between bluetooth enabled phones.
To be honest, it's a bit of a waste of time. A neat trick, but that's all. It's quite high-bandwidth compared to an IR port and a lot more convenient, but for remote data the bottleneck is in the phone line (such as it is), and not the connection between the phone and the device so there is little speed benefit, and getting the phone out and placing it next to the Laptop isn't exactly chore-of-the-decade, is it?
The best use of bluetooth is in wireless handsfree kits. Basically (for about 50 pounds) you get an wireless earpiece and boom mic that will work with any bluetooth phone. Your phone can be in your pocket, even in the next room, and you can still talk on the phone. Clearly this has health benefits, because you can be farther way from your mobile's Microwave transmitter. And it's far more convenient than a "wire" is most of the time. These are really neat, and once you've used one you'd never go back to a regular hands-free kit!