The headline above paraphrases Time Magazine's Michael Scherer, criticizing the Obama campaign for pointing out McCain's long record of opposition to alternative energy. Scherer points to promises McCain is now making and says these outweigh his record, even if the promises are vague.
Some historical figures may disagree with that analysis. See Gristmill for a different view. I'll just add one additional point, that one can look to a candidate's record for an assessment of his judgment. Even if every promise McCain now makes is sincere, his record of past mistakes is an appropriate argument for voting against him because he has bad judgment.
UPDATE: Scherer admits that examining the record is a legitimate technique, so some credit where some credit is due.