How harmless are those bicylists, really?

Yahoo! News - Police and Cyclists Continue Legal Battle: "Critical Mass was started in San Francisco in 1992 with the goal of making a statement about cyclists' rights and has since spread to cities around the world. " AP ran this "interest" story about New York's current Critical Mass problem. I remember it well from San Francisco, since I was pregnant during some of the movement's most critical traffic foul-up masses. My worst fear was that I'd go into labor on a Friday afternoon, and somehow have to get from my home to the hospital through that jammed up traffic. Basically, Critical Mass is a cute theory -- let's remind everyone how useful bicycles are -- but I wonder how many people have gotten tangled up in a law of unintended consequences resulting from massive downtown gridlock. (BTW, I was lucky and ended up going into labor at a non-Critical Mass time.)