Is the Palin Parody Illegal?

Going Rouge, a liberal takedown, will debut on the same day as Going Rogue

A liberal takedown of Sarah Palin, Going Rouge, is set to hit stores the same day as Palin's own set of essays, Going Rogue. (Read those titles twice in case you missed the difference.) The two covers look remarkably alike. Plenty of people are wondering whether Going Rouge might cut into Palin's sales, but Thom Geier at Entertainment Weekly and Allahpundit at Hot Air have a different question: Is such a copy-cat cover design actually legal?

Asking if these jackets are "fully kosher," Geier wonders if, "[a]t the very least, ... some hockey-mom-loving conservatives [might] be confused enough to pick up the wrong book?"

"Good question," replies Allahpundit, who declares his "memory of trademark law" a bit "rusty" and opens up the floor to his lawyer readers:

Can the entire layout of a book cover qualify as a trademark for legal purposes? Even if it can, doesn’t the subtitle "An American Nightmare" on the cover of the lefty book defeat the argument that the design is confusing? (If not, is there some sort of "parody" defense?)