I found this on YouTube And I haven't heard of it as a method of dispatch here in the UK. I just offer this link for information and discussion, I've not done it this way, so am not recommending it, though in the video the chicken appears quiet and calm and not in distress, and I like the woman's approach to the task - businesslike yet compassionate.
http://youtu.be/5_S3P0eU0lE
http://youtu.be/5_S3P0eU0lE