I was in some random little town in Austria last summer and rode on a street with cobblestones and a street car that ran right down the middle of the street. At some point (near a river), the rail lines veered right (you know, into what would be a bike lane), and i had to dismount and lift my bike over the rail lines. Aside from the scariness of parallel lines to where I am riding, street cars seem to be a good way to get people around a city. Just be careful of getting your tire stuck in one of the rail lines... I have heard horror stories (particularly on skinny road bike tires).