I do believe in corporal punishment. It can be applied in one of two ways: to inflict pain as a deterrent to future episodes of misbehavior, or as a means of deflating the child's ego and encouraging submission to parental authority.
As a child, I was corporally punished both ways. My mom used a switch to inflict stinging pain, while my dad only used a ping-pong paddle to apply a couple of mild swats to my backside. My mom would accompany the switching with explicit threats of similar treatment the next time I misbehaved. My dad would make no threats, but would express his disappointment that my misbehavior had made this paddling necessary. I personally found my dad's technique to be much more effective.
I believe that a child's misbehavior is often an affirmative expression of rebellion against parental authority, and a means of testing the limits of a parent's patience. The rebellious attitude and the testing will cease when the authority and the limits are clearly established.
I admire those parents, such as duffsmom, who succeed in maintaining parental authority by means other than corporal punishment. I just never managed to find the secret of doing so.