I present to you, our auto-tracking ball cannon:
Our entire Strategic Engagements Team held a hackfest to build something fun and awesome, and, as you can see from the below video, we did just that!
The 8 ball launcher is set on a platform and connected to several actuators and a solenoid to allow it to control the cannon's pitch, yaw, reload mechanism, and trigger. The mechanical parts are controlled by the Arduino Yun which exposes an API that is consumed by the OpenCV program that tracks our target.
For full details of the parts and the setup, check out: http://github.com/jpoon/ballblaster.