Street Photography.

Question: What is street photography?
Ans: Simply put, it is taking pictures of people going about their daily business "in the street", sometimes without letting them know.
Question: Is it ethical?
Expanded question: Is it proper to take pictures of people without asking for their permission in the first place?
Ans: Ok, people, this is a personal opinion. Here goes: I believe that as long as your intentions are good, it is fine. Let me explain: by good intentions I mean that you are not trying to violate someone's privacy for profit, you are not stalking someone, you do not plan to take embarrassing or revealing pictures.
Why? Simply because an 'aware' subject is no longer a natural subject.
Discussion: of course, it is very difficult to draw a line between art and something of a more salacious nature, but I am putting some value on the personal morals of the photography.
Profit: something that I leave open to discussion. I am not a professional, so this is not an issue that I have had to deal with, but it is pretty much an open question... do you share profit, if any with the (unknowing) subjects. A rather knotty problem.
I leave this post with a couple of street pictures. Comments welcome. Also check the wikepedia entry here.