I research Bluetooth Smart security. I've spoken about it at ShmooCon and ToorCon.
Bluetooth Smart goes by many names. I refer to it variously as Bluetooth Smart, Bluetooth Low Energy, Bluetooth LE, and BTLE. They all refer to the same thing: a new modulation mode and link layer packet format for low-energy Bluetooth applications defined in the Bluetooth Core Spec 4.0 (warning: big zip).