Everyone from my office will be attending this. I'm curious to see if a mob of tech nerds will be taken more seriously by the powers that be than occupy wall street people.
What on earth would you be worried about? Getting asked to leave? Having to look at a police officer?
Combine that with pointing out that he has admitted he is in favor of censorship and you have the ultimate head-line (especially if somebody brings their kids).
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.
If you care about the internet AND/OR you want to show that such tactics don't work, do show up. Otherwise, sit back, relax and get ready for an internet that looks like network television.