it is BLE or BlueTooth 4 ( same thing) , small difference is that iOS supports a HID over the more standard Gatt profile . Ultimately the end the BLE 'beacon' - 'bug' - 'responder' device is likely a TI CC2540 chip or similar mfg ( I think there is another swedish mfg that provides a similar system )
Just a nit, but BLE and Bluetooth 4 are not the same thing. The Bluetooth SIG has made complete mess of the situation. The Bluetooth 4 specification defines both BLE and Bluetooth "Classic" which use different radios. You can label something Bluetooth 4 when implementing only one of the modes or both.
The marks you need to look for are Bluetooth Smart and Bluetooth Smart Ready. Bluetooth Smart is reserved for devices that only implement the BLE radio and this is what you'll see on things like FitBits, etc. The Bluetooth Smart Ready is reserved for devices that implement both Bluetooth Classic and BLE. The iPhone 4S+ is Smart Ready, Android 4.3 will be Smart Ready, etc.
It has already bit Nike in the butt when people flipped out when they said they weren't going to support Android with the Fuel Band. The reasons were completely technical, but consumers assumed it was because Nike was some how saying Android was inferior. Of course, trying to communicate this in a tweet also makes the problem even worse.
