If I never see another image of a person leaping from those buildings, it will be fine with me. I like to think I've got a pretty thick shell, but those images above all others from that day, still cause some strong emotional and even physical reactions in me.
Watched an interesting show on The History Channel last night about the attacks called "I Witness" and everytime they showed footage of someone jumping, I conveniently decided it was time to get up to grab a beer, let the dog out or check on the grill. Great show though, completely uncensored. You get a real feel for the sheer anger, fear, sadness, helplessness people there felt as it was happening. A couple times, I caught myself thinking "would I have reacted any differently?" If it's on again, it's a powerful show.