It's clear abstinence-only education doesn't work, and it has nothing to do with the Bristol story.
Well actually that may not be entirely true. I admit that this is nothing but speculation, but one could make the argument that if Palin was for comprehensive sex-ed, her daughter may have been much more aware of the consequences/risks of unprotected sex and made a more informed decision prior to the act.
Of course kids being kids even with that knowledge she may have ended up in the same situation anyway, but more education couldn't have been a bad thing.