If SOPA passes, every user-generated content website is going to have tremendous costs, in many cases prohibitive. I think only Facebook and a few players would have the resources to police their content. This is going to be really bad for Silicon Valley and the startup community.
Actually, thanks to the economics of computer startups, the big players, if they were held to the same standards as everybody else, are worse off. They have fewer people-per-post than smaller sites, not more. It's that whole scaling thing that is the reason why computer startups can be so exciting and lucrative.
Of course, the key phrase here is "if they were held to the same standard as everybody else". Though I think the second-order effects of SOPA would be more bizarre on something like Facebook than you'd think at first blush. The mere fact that they could still be legally shut down in a heartbeat still can't help but have a profound effect on their world even if the trigger is never actually pulled for fear of generating an uproar.
