I was riding south on Broadway on the left side of the road with a few other riders. There were maybe 10 or 12 of us, and we were stopped, as we rode up, by a large number of cops on motorcycles who immediately targeted people with cameras and then started writing us tickets. We were riding next to some barricades that separated a pedestrian walkway from the road, and we were in a lane that has the picture of the bicycle, showing us that just through the traffic light (where we were stopped) is where the bike lane begins. The cops demanded our IDs and would not say why, then spent a long time writing tickets, talking amongst themselves. They returned our IDs with tickets, such as "failure to stay to curb" and "riding abreast of another cyclist." When I asked what I had been doing wrong, since I had been riding in the road, as I am allowed to do, the cop ignored me several times and then said, "You'll have to take it up in court" and walked away.
It was pretty clear that the cops had been waiting there for critical mass riders and that they didn't care what they were giving tickets for.