Now that I've seen the movie, I can safely agree with Ann Hulbert: Juno is a film about hot-button subjects (abortion, teen pregnancy, adoption, etc.) that succeeds artistically precisely because it complicates, rather than over-simplifies, every one of the thorny issues it raises. The only thing that's remarkable about this cinematic approach to controversy is how rare it is in Hollywood: Juno's shades-of-gray approach the culture wars ought to be required viewing for Brian De Palma, Paul Haggis, Robert Redford, and just about every other Hollywood filmmaker who's turned out a lousy movie about the Iraq War in the last year or so.
The real flashpoint issue in the film, of course, could have been abortion. Here [Diablo] Cody's politics (presumably pro-choice) are at odds with her plot needs (a birth) and, who knows, maybe commercial dictates, too, if studios worry about antagonizing the evangelical audience. It's a tension the screenplay finesses deftly, undercutting both pro-life and pro-choice purism. Pregnant Juno at first reflexively embraces abortion as the obvious option, and her best friend is at the ready with phone numbers; she's helped other classmates through this. But just when pro-lifers might be about to denounce this display of secular humanist decadence, Juno stomps out of the clinic, unable to go through with it.
She isn't moved by thoughts of the embryo's hallowed rights, however, but by a sense of her own autonomy. And for her, that doesn't mean a right to privacy, or to protect her body ("a fat suit I can't take off," she calls it at one point). Juno is driven by the chance to make her own unconventional choice.
Well ... sort of. I would say that Juno goes further than Knocked Up in presenting abortion as a plausible choice for a girl in the heroine's position, and doesn't go nearly so far as Apatow's movie in making the advocates of abortion look like heartless creeps. And Hulburt's right that Juno McGuff's decision to bear her child to term is an act of personal autonomy that's of a piece with her broader nonconformity, and that deliberately sets her apart from the conformist (and judgmental) world of parents and teachers and too-chatty ultrasound technicians.
However, the crucial decision isn't cast as a Dead Poets Society-style validation of nonconformity for nonconformity's sake; it's cast as a case where being a nonconformist happens to be the right thing to be. And while Juno may not be moved by thoughts of her embryo's "hallowed rights," exactly, she certainly seems to be moved by the unremitting grossness of the abortion clinic (complete with a pathetic-seeming girl receptionist who tells her that they need to know about "every sore and every score") - and more importantly, by the declaration, from a pro-life Asian classmate keeping a lonely vigil outside the clinic, that her child-to-be "already has fingernails." (Careful viewers will note that while Juno sits in the clinic, filling out paperwork, the camera zooms in on the fingernails of the other people in the waiting room.) Just as the movie as a whole charms viewers (and particularly critics) with Juno's hyper-articulate tomboy cynicism, but ultimately asks us to admire the idealism at work under the cynical shell, so too does the scene at the abortion clinic invite the audience to giggle at the Asian girl's pro-life idealism ("all babies want to get borned," is her lisping chant), while simultaneously giving her the sincere line that makes all the difference in Juno's decision.
None of this means that movie is a brief for overturning Roe v. Wade; far from it. But like Knocked Up, it's decidedly a brief for not getting an abortion.