First, the Business Software Alliance (BSA) is breaking ranks with other members of the IP Mafia and are reversing their previous support for SOPA.
(previous supporting statement here)
This is enormously significant because RIAA, MPAA, and other bill supporters have worked hard to portray this as infringers and those who profit from piracy v. honest content providers. That BSA now says the criticisms are legitimate and must be addressed is a serious problem for the usual strategy of marginalization and ad hominem.
Similarly, this ope ed in the Daily Caller is highly significant as it negates the effort to persuade the Tea Party and other Libertarians opposed to Internet regulation that SOPA is utterly benign and only socialist orgs like my employer oppose it.
Next, it is wroth noting how much damage SOPA is doing to our foreign policy and pro-democracy initiatives. Russia and Al-Jazeera are saying the U.S. now ranks with China in Internet censorship. http://www.techdirt.com/articles/20111120/22021716846/how-other-parts-world-view-sopa.shtml
These stand in sharp contrast to efforts by the RIAA and the MPAA to downplay the problems with the bill:
Finally, PBS analyzes how the Internet exploded over this issue, with a nice shout out to PK at the end.