I have only cussed out a few motorist while on my bike, usually they are surprised that I caught up with them. I usualyy just says what needs to be said, a little venting is usually a good thing for me. My attitude has changed a little on this though. Last year, while my girlfriend and I were walking through a crosswalk, a guy swerved to hit us. I gave him the finger. he then stopped his car in the middle of the road, left his wife and small child in the car and came after me. He backed down when he saw that I wasn't moving, but the whole incident made me look at the confrontation thing a little differently. I certainly do not want to get my ass kicked any time soon.
I think each situation needs to be evaluated, and I am sure my temper will get the better of me when a motorist cuts me off, or hits me, or something like that.