This post by Joe Ito reminded me about the same ethical/shyness issue I have when taking photographs. I don't feel comfortable taking a picture of a stranger without first asking their permission. Obviously that can sometimes ruin the photo as the interesting pose or facial expression they had that inspired you to want to photograph them is now gone. On the other hand you never know if someone might get offended (or worse) if you take a photograph without asking first..
A friend of mine, who is a great photographer, photographs without asking permission. She will literally walk up to a person, stand in front of them and take a picture of them. I've even seen her do this without even thanking the person afterwards.. she'll just walk up, shoot, look at the picture on her camera, walk off!
I don't know.. I wouldn't be surprised if this is one of those 50/50 things where some people think it's cool and some don't. What do people think? Is it ok to photograph strangers without asking first?