In Connecting to Intel® Edison from Android* with Bluetooth* LE (BLE) describes a way to access BT via Arduino code but additional BT shield/kit is required.

Arduino 101* includes on-board Bluetooth® LE to enable developers to interact with Bluetooth®-enabled devices such as phones and tablets.

Arduino enthusiasts searching for a board that supports connection via Bluetooth rather than USB may be interested in the Z-duino Bluetooth Arduino board recently launched via Kickstarter.

The $22 kit includes an Arduino-BLE board and 6-pin header that should be fairly broadly applicable for building Arduino-based hardware that can communicate with iOS devices.

The Bluetooth Controlled Speech Recognition Unit: This bad boy is simple, and easy to use. With the help of the free AMR_Voice App, you can control 10x Arduino compatible outputs.