The team behind Stop Watching Us says:
"Since the Snowden leaks started, more than 569,000 people from all walks of life have signed the StopWatching.us petition telling the U.S. Congress that we want them to rein in the NSA. On October 26th, the 12th anniversary of the signing of the US Patriot Act, we're taking the next step and holding the largest rally yet against NSA surveillance. We'll be handing the half-million petitions to Congress to remind them that they work for us — and we won't tolerate mass surveillance any longer."
Organizers are in a reddit AMA right now.