Saw a cyclist going the wrong way on a one way street almost get whacked by a driver going the other (correct) way making a left on a green light. If you're going the wrong way, especially at a nontrivial speed, there's a pretty good chance that a driver isn't going to notice you. They're going to scan for pedestrians in the crosswalk, then go. If you pull out into the intersection there's a good chance you'll be roadkill. They're not going to see you because you're not supposed to be there.
