I think that the friendly driver thing is bullshit. That's coming from an ex-New York Bike Messenger. I got hit by several cabs, rear-ended by a bus, and right-hooked by a cement truck in NYC, but no one in seven years of biking in New York threated me for riding on the street, or swerved at me like they do here. In Pittsburgh, I get verbally threated all the time, swerved at, deliberately/maliciously cut off and near-right-hooked.
My analysis: the Pittsburgh Left is cute and all, and maybe drivers are more friendly to other drivers. But, and this is key, Pittsburgh drivers don't expect cyclists and don't know how to react to them on city streets. This is the result of years of stupid car-centric urban planning, poor driver education and this fog-a-mirror-get-a-license DMV and DOT. Most unprepared drivers (suburbanites and sports fans) seem startled to see me on the street. Some translate that fear of the unknown to knuckle-headed threats and worse. Signs, paint, and better driver ed could fix this.