Last week a cyclist was doored and knocked under a bus; according to a comment, the victim is expected to survive.
I don't get reflexively angry about people who door bicyclists in the way that I do with those culpable for other traffic accidents. I didn't regularly drive in a city with a substantial bicycling population until I was in my mid-20s, which meant that my driving (and parking) habits were already ingrained by the time I got here. I'd like to think that I always checked when opening my door—but it's also possible I didn't start doing it religiously until I started biking and/or had friends who got doored. I sort of suspect that's the case for a lot of people, since most American non-metropolises not only have few cyclists, many of them just don't have that much on-street parallel parking, so I don't think it's a habit most people get into.
Anyway, I guess what I'm saying is: always, always check for cyclists when opening your doors.