Arduino boards get a Bluetooth Smart dev kit from Nordic Semiconductor. The SDK is compatible with a range of Arduino, ChipKIT shields that employ the nRF8001 Bluetooth Smart connectivity device.

The phone uses an app that talks to the Arduino via Bluetooth, which means the Arduino ... We sort of prefer a more obvious chess robot, but that’s just us.

[Labpacks] wanted to build a robot car controlled by his phone ... build a phone interface that will talk to your hardware over Bluetooth LE, USB, or Ethernet (including WiFi).