Well, so much for the whole "She's a raging abstinence-only crusader" argument. Lazy readers please note: the "clarification" is also from 2006, and therefore is in no way a response to Bristol's pregnancy or the current campaign.
This is what happens when politicians are vetted in the press; one incomplete piece of information comes out, and one side goes shrieking through the meadow either in glee or outrage. Then another piece of information comes out, and people look stupid. I'm sure another piece of information will come out next week to swing the pendulum back the other way.
Of course, I expect the immediate reaction to be "OMG FLIP-FLOP," rather than "Oh... well okay then, that makes more sense."