[danso]

Police are perfectly behaved when the proper permits have been filed...Here's a photo I took of when the hundreds of pilots protested on Wall Street (also at the same time as OWS): http://www.flickr.com/photos/zokuga/6190171031/

And for protests without permits...the cops are generally going to not do anything but watch unless there's an imminent public safety issue. They don't like bad publicity as much as the next person, and I imagine they're going to be particularly wary of very tech-savvy groups, for obvious reasons.