The United States has filed a brief opposing the GBS settlement (PDF) that doesn't go nearly far enough... but it is probably sufficient to cause Judge Chin to reject the settlement as it is written. The most interesting thing about the objection is the silent spaces. It does not discuss copyright law or theory anywhere... and, in particular, does not discuss any of the implications of § 411's registration requirement as jurisdictional (the law in the Second Circuit, although IMNSHO it's wrong) and how the Supreme Court's opinion in Muchnick (PDF) (due in the next nine months or so) will affect that. Further, it does not discuss the mechanistic conflict between an opt-out class and the fundamental inability to opt out of copyright.
Somewhat more disturbingly but not too surprisingly the opposition does not extend its discussion of the adequacy of representation to intraclass conflicts in treatment of nonorphan works. This is an extremely technical, fact-intensive inquiry that is not really within the proper scope of inquiry for the United States in this matter. Similarly, the opposition brief does not discuss the interplay between antitrust law and the adequacy of representation issues... nor does it mention the elephant in the room, although that's not too surprising on a factual level; the US Attorney for the Southern District of New York probably doesn't care a whole lot about preliminary injunctions from a decade ago that have no criminal-law implications.
This is significant food for thought.