I did something similar, but with just a webcam and a laptop, and instead of beer it was mead. Basically, I pointed the webcam at the air lock, which produced a bubble every 15-30 seconds (depending on the fermentation process). I wrote a small Python program using PIL which processed webcam frames and detected sudden changes in the image (a bubble). Each time a bubble was detected, it would write an entry to a database (date, time_delta_from_last_bubble).
This was really cool when I went out of town because I could login and see the delta between bubbles gradually increasing, and once I saw it sitting at 40-50 seconds between bubbles for a day or so, I bottled it.