Bluetooth is really the infrastructure for fast wireless short range access. It has some other interesting capabilities such as recognition of the type of component and being able to register it into the network.

So if I walk into the room with a bluetooth device where there are other bluetooth devices they will recognize each other and allow you to use the resources. So put a bluetooth capable cell phone in the area of a bluetooth capable PDA the PDA can use the phone (wirelessly) to dialup the net and get your email.

When I was with Deutsche Telekom in the very early days of Bluetooth there were high hopes that this would become the high-speed wireless LAN standard. After the failure at CBIT a couple of years ago, and the advent of 802.11b (and 802.11a) being so inexpensive Bluetooth is slow to get moving.

Here's a quick magazine article about Bluetooth.
http://www.redherring.com/mag/issue78/mag-bluetooth-78.html