So, Barack Obama opted out of public financing. Is it a flip-flop? Sure, but really, he'd be an idiot not to do this, given his fundraising skills. The idealist in my does not like it; the realist knows it makes sense.
James Joyner writes thoughtfully on Obama's inconsistencies. In short, he did indeed pander on NAFTA, which he's now, wisely, backing away from. On foreign affairs, though, flexibility and learning are GOOD traits, while trying to honor, if possible, basic principles. Obama, I think, can do this. I'm not convinced with McCain.
So, a good leader, then, doesn't just follow polls. But flexibility, even reversing yourself, is a must, as well.