What struck me in this episode was most of the staff's inability to recognize a Beatles facsimile coupled with the ending of the Cool Whip scene ("You can't smoke in here"). Has anyone disallowed smoking on the show yet? We're approaching a sea change--the late 60's--and we've known that for a while now, but I think the fact that Don's (and SDPC's) only tether to the Beatles/contemporary culture is Megan signifies that she'll be the key to keeping Mad Men (and the Mad Men) topical.
I'm not good at symbolism, though. Tomorrow never knows? So next is Sgt. Pepper? Someone already did LSD. Or the baked beans ad will end up using baby doll parts and then scrapped altogether.