The sensor forms an image and OpenCV detects the actual touch configuration. It appears you can use the raw data from the Arduino, too, but it might be a little harder.

Capacitive touch sensors are entirely in the domain of DIY, requiring little more than a carefully-chosen conductive surface ...

Engineer Saeki Yoshiyasu created a system that allows him to connect to a server with his iPod touch and draw a design on the web browser using nothing but a Graphics LCD, an Arduino, and a WebSocket ...

If you have a few hours spare and fancy creating a new Arduino project in your spare time you might be interested in this fun Arduino infrared touchscreen music controller which has been created ...