According to the latest regular issue of Entertainment Weekly (they released two issues this weekend, but one is an American Idol special)--#936, June 1--in an upcoming rock 'n roll mockumentary, Walk Hard, Paul Rudd will play John Lennon and Jack Black will play Paul McCartney in a scene where the two get in an argument.
Tenacious Beatles at Penny Lane During the Holiday in the Knocked-Up Anchorman's 40 Year Old Destiny?
Okay, that was extremely contrived and probably not that funny. But I'm psyched at this news, probably because I haven't been able to stop laughing at the idea since I first heard it.
Choice quote from Rudd?
"To think that Yoko Ono would even see it makes me want to throw up."
This, however, does make the casting a bit more plausible: