According to Corey Menscher’s portfolio site:
The Kickbee is a wearable device made of a stretchable band and embedded electronics and sensors. Piezo sensors are attached directly to the band, and transmit voltages when movement underneath is detected. An Arduino Mini transmits the signals to an accompanying Java application wirelessly via Bluetooth. (A SparkFun BlueSMIRF v2 module that communicates serially with a Macbook Pro)
The Java application receives the sensor values and analyzes them. When a kick event is detected, a Twitter message is posted via the Twitter API.