I am the author of Bluesnarfer, a bluesnarfing utility for Linux.
On some mobile phone models, you can bypass the bluetooth authentication and take complete control of the phone, reading the phonebook, SMS, doing phone calls, etc.
Bluesnarfer enables you to exploit this vulnerability.
For more information about bluesnarfing, take a look at this page on wikipedia.
Bluesnarfer is actually included in the most well know penetration testing Linux distributions.