In this interesting article on InfoWorld, Chad Dickerson tells us how he used Bluetooth and mobile technology to get where wi-fi couldn't.
The article in itself doesn't say one technology is better than the other, and it doesn't even compare them. Actually he talks about connecting to the internet via mobile networks, and using Bluetooth to connect a data terminal (the laptop) to the modem (the mobile phone).
The story is so funny at one point: ""Are you on the Internet??!!" She said, "Yes!" The military guy turned around to everyone around him and announced, "Hey everybody, this woman over here is on the Internet and I don't see NO WIRES!" He waved his hands around an imaginary computer, like a magician performing levitation. His gestures were met by nods of amazement all around."