Since we live on a peninsula, there is a fairly narrow corridor I can ride as I approach my house and I frequently meet up with random cyclists along this part of my commute. Typically, I'm best matched up with racers who are out for a "day off", they cruising along at a pretty good commuting pace and it gives us a chance to chat. Over the past few months, I've discovered that I'm apparently developing a reputation. Almost all of the people I meet ask whether I'm either "that commuter guy" or "the guy that moves with panniers". Obviously, my bike is noticeable enough that they either see me in person or have heard mention of my great commuting feats during races.
This is another great example of how different your interactions are with those around you when commuting by bike rather than car. In a car, you certainly get to the point where you recognize other people who commute the same way you do, but do you ever interact with them? I'm curious what the bike culture is like in Europe, do they act more like drivers and keep to themselves or are they frequently having rolling discussions with different people. I guess I'll just have to do a field study some day.