Marc Ambinder writes:

Sen. John McCain knew. A few members of his senior staff knew. Most members of his senior staff did not know. Palin’s spokesman in Alaska did not know. Palin’s campaign-appointed spokesman did not know. McCain staffers — at different levels of the campaign — are a bit stunned.

Really? The whole town of Wasilla seems to have been in on the secret. Time reports:

So his name is Levi.
That’s about the only thing that I didn’t know about Bristol Palin’s pregnancy. The rest of the details I picked up almost without trying, while talking about other things with townsfolk – some who know the governor and her family well, some who don’t. It was, more or less, an open secret. And everyone was saying the same thing: the governor’s 17-year-old daughter is pregnant, the father is her boyfriend, and it’s really nobody’s business beyond that.