The rally in New York City outside the offices of Senators Schumer and Gillibrand that Rachel described in the SOPA/PIPA segment was organized by the NY Tech Meetup community.
ADDING: As long as I'm posting follow-up links, this is the very excellent treatment of the issue by Up with Chris Hayes from this past Sunday that Rachel mentioned tonight. NBC Universal vice president, Richard Cotton, at least makes it clear why legislators would have signed onto the bill in the first place. I'm not sure why he keeps using the phrase "wholesale devoted to theft/illegal activity" since I don't find that expression in the bill text. (pdf) (TechDirt delivers a pretty impassioned rebuttal to many of Cotton's arguments.)