Let's hear it for the new girl on Mad Men! Ok, yes Don's new girl is quite comely, but that's not what I was talking about. And yes, Bobbie is sort of a new girl as well -- especially when juxtaposed with Rachel in that scene in the bar -- who has turned out to be a fascinating character. But again, not the new girl I was talking about. The new girl to which I cheer, is in fact Peggy -- who we can safely say is no longer the doe-eyed "new girl" we saw in the very first Mad Men episode, referenced in this episode with Joan again showing around another new girl. Thanks to a flashback of her and Don -- and some pointed career advice from Bobbie -- Peggy is now more like Don than even Don is these days.
Speaking of Don not being himself, while he recently seems to have gotten some of his mojo back, he's had to screw himself to do it. If you think about it, Don really latches on to people where he sees himself. In Midge, he saw his artistic interests. Rachel was the exiled independent, who's mother died in childbirth. He's even fond of Bobby mostly because he sees his former self. But where little Bobby is his Dick Whitman, big Bobbie is the self-actualized Don, in female form. "This is America, pick a job and then become the person who does it," says Bobbie to Don, in explaining how she got where she is. Don, for his part, pauses and slowly puts on a sly grin before nodding in full, Ayn Rand-approved agreement. Having Rachel show up there (now Mrs. Katz) is a reminder of that, and also became the impetus, I think, for Don agreeing to head up to her place on the beach.
Don drives Bobbie up there and the whole exchange is fittingly backed by the song "Theme to 'A Summer Place'" by Percy Faith and his Orchestra. The song was a number one smash in 1960, but more importantly, it's purpose as the theme music to the film A Summer Place says so much more. Not only is the song and film a nice reference to them driving up to Bobbie's beach house, but the film's themes of infidelity and it's consequences are right on target. Of course, some consequences become quickly apparent, with Don swerving off the road and flipping his car. 
The real drama comes after that, though, in finding out that it's Peggy who bails Don out. This, of course, leads to the flashbacks of Peggy in the hospital, revealing that Don was involved in helping her clean up her mess, so Peggy owes him. But it's what he says to her in that flashback that tells us even more: ''Get out of here and move forward. This never happened. It will shock you how much it never happened.'' Even though that's pure Don speak, it tells us so much about why we see Peggy so repressed this year about her child.Peggy not only took Don's advice, but she's also now absorbing Bobbie's cutthroat feminist approach, by not trying to play the game as a man, but as a woman who's Don's equal. When she subtly reminds Don that they're even now, her coming out party started when she said "Thank you, Don," dropping the Mr. Draper salutation for good. It was a great moment, and Don's reaction seemed to at first be startled, but then understanding that the score is now even.
More:
The other song appearing in the episode was, sort of, Mozart's "Eine Kleine Nachtmusik, K. 525 - Allegro," being played on Freddy Rumsen's trousers, a moment of comedic surrealism:
Ken was failing badly trying to pick up Don's new secretary, Jane, but it's still an embarrassing way to wriggle off that hook. But while the rest of the office males are drooling over Jane, notice how Don doesn't even give her a second look. Is it that he can't see anything of himself in her? Also, you probably noticed Peggy's sister Anita looked very pregnant checking on Peggy in recovery. Not sure how much time had passed at that point from Peggy's delivery, but it adds another wrinkle to the story. Is that her child we see? Or is Anita already acting pregnant (pillow under the dress) to help cover for Peggy? Or did Anita lose her child? Any of these scenarios may change how we look at her jealousy/resentment towards her younger sister.
Previously: Rebirth of a notion (Episode 2.04)
