I think the important thing is real chilling for free speech. After all, this is just a parade. But if you're involved in anti-recruitment or anti-war or any group doing anything important in town that you know you're secure from police invading your private homes.
Since 9/11, we've created a culture in which security is more important than liberty. The NSA is tapping your phone calls and email. The Pentagon is infiltrating your peace march. Actions at the federal level have a trickle down effect that has emboldened local law enforcement. When the president says 'Safety at any cost,' local cops take that to heart.
If you think you have to be doing something wrong to be the target of police surveillance, you are naive. All we are doing is organizing an event for the entire community.