Skippy,
The project basically emulates the remote EOS control via a PC with the following significant differences:
- replaces the PC with an Android application on a phone or similar device.
- Makes the interface wireless via bluetooth.
The thing plugged into the camera is just a microprocessor/microcontroller - this one is called an Arduino - and it provides the interface to the camera and bluetooth (via "shield"). One could do the same thing with a PIC or other...this one was just already designed and programmed.