I forgot about that Gizmodo fiasco. I wonder how that all turned out, or if it even has yet. IIRC, they were trying to claim privilege under the new (and not legally tested or developed) CA Reporter's Shield law, which I believe the Court found wholly unpersuasive when it refused to quash the subpoena.
Such a assertion here will have virtually no chance of success for defense. Oddly enough, intellectual property law is much more robust than real property law in this regard. For instance, even if Gawker says someone delivered the book to them unsolicited and anonymously, that doesn't give them the right to publish it, even if they're telling the truth.
I'm pretty sure they're screwed here. I foresee settlement negotiations in Gawker's more immediate future.
I think the main issue also is that the copying of complete pages does not fall under fair use. Excerpts are legal under the guise of criticism but are limited to the threshold of affecting the commercial value of the product. This becomes even more so the case because the book hasn't even been published yet so these illegal leaks are even more detrimental to the commercial value of the product.
The bottom line is wholesale copying of unpublished pages is not a legal form of criticism allowed under fair use laws. Gawker knows it but they are playing dumb to the brain-dead choir while trying to insult Palin's intelligence.