Since no one asked me my opinion here it is anyway. Cars are so well insulated and comfortable to drive that things like critical mass are trying to break down a brick wall with a teaspoon. The people that are most likely to be reactive to them are the ones that are having a really bad day, and we all know how that ends.

I participated in a valentine's day bike ride down here, and the organisers contacted the city council to check on the legality of what we were doing. They were told that groups of bikes are treated the same as large slow moving vehicles - think wide load trucks, etc. If you were crossing an intersection we were allowed to ride across as one but deliberately blocking an intersection against the lights is just boneheaded and discourteous, and not really in the spirit of our event.