No, not the much-hyped Cate Blanchett in “I’m Not There” or Adam Sandler in “Reign Over Me.” The most devastating send-up of Mr. Zimmerman is by John C. Reilly in the bio-pic satire “Walk Hard: The Dewey Cox Story.” This Dec. 21 comedy is a hit and miss affair, but spoofs of Dylan and The Beatles (Jack Black, Jason Schwartzman, David Krumoltz and Justin Long) squarely find their targets.