At the risk of being ostracized...I think there is a time and place for spanking. Not to the extent that most people think of though. Too many people use spanking, hitting, slapping, whatever as a shortcut because they lack the patience or skill to deal with a misbehaving child.
Spanking a child because he can't sit still at the hall is wrong. Expecting a two year old to sit still during a boring religious service is expecting too much and a parent that hits a child for being restless is bordering on being abusive.
Reacting out of anger or impatience and hitting a child is wrong. It's also abusive. Hitting out of the moment of anger or frustration is not discipline.
When is it the right time to spank a child? I can't answer that. Some never need a spanking, other forms of discipline work. Others might need a little time behind the wood shed to impress upon them the importance of obeying a parent.
My parents were not ones to spank a lot. In fact I can remember most of the times I got it. I deserved it I might add. But I also remember my mother lashing out in anger and hitting me one time. I was wrong then too but it wasn't the hit I remember but the fury and anger behind it as she lost her cool and lashed out at me.
My father only hit me one time in my life. I deserved it also. I wasn't a child but a teenager. A sullen, disrespectful, angst filled teenager. After getting the wrong tone of voice out of me during a serious discussion about my bad attitude, he smacked the shit out of me, but good. But instead of leaving the situation on a violent note though, he picked me up, yep, he hit me that hard, and he hugged me hard and cried and told me that he loved me and didn't want to see me get in trouble. Some might say that was abuse, but being the only time he ever did it and after being constantly provoked and it wasn't in anger I can say that is was the only thing that got thorugh to me at that time. So in that case, that type of discipline was correct.