I dont think I would ever smack a baby- but at 12 months i dont think they are 'babies' as such any more. I will not be afraid to smack Riley if he is being really naughty but i dont think intimidation and fear are the only way to go. I got smacked when i was little and although it did help me be good it was onyl out of the fear of knowing i would get it when i got home and i dont want that kind of 'control' over Riley regardless of how old he is.
I also think there needs to be a distinguishing difference between a smack and inappropriate behaviour. I used to get smakced with a plastic spatula and that is inappropriate (or unappropriate??) but i dont think a smack on the hand or bottom hurts anyone especially if it helps a child to 'remember' that this is a bad thing to do- e.g. walk out onto the road- touch an oven.

Mind you this may all change once and if I have a naughty 2 year old!!