
Interesting technical problems like this one
are what get people interested in computer science as a career.
Its great to hear about them.
Sort of along similar lines, face recognition is a similar use of machine vision.
Here is one overview on how it works.
http://cnx.org/content/m12534/latest/
"Veggie Vision" is another very interesting computer vision project that could be coming to a supermarket near you soon:
http://domino.watson.ibm.com/comm/wwwr_ ... ne399.html
This kind of technology is becoming affordable very quickly as the price of hardware comes down.