It depends on the situation. In general I am extremely cautious about passing to the right of motor vehicles. The photos posted by [MENTION=106798]10 Wheels[/MENTION] above are very illustrative of different situations, and I agree with all of them in those situations.

There are instances when I will filter up to the right of cars waiting at a red light, usually in this situation there is a bike lane. One very important aspect of bike lanes that many cyclists, and even fewer motorists, know why, is that they go from a solid white line to a dashed white line 100-200 ft before an intersection. This is to allow changing lanes. Cars turning right are to move over into the bike lane transition zone so bikes can move over to their left.

When pulling up to a light in this situation, I always pull far enough to the left to allow cars coming from behind to turn right without having to cross in front of me.