A Brief History of Calibration
The definitive Apple support article for notebook battery calibration has always been Knowledgebase Article 1490. Note that the last modified date of that article is August 4th, 2011. It changed in July 2011 as well, but the August 4th edit just re-arranged some of the new content that arrived in July. Prior to July 2011, the article did not contain the section titled “Portables with built-in batteries” and the sentence, “Current Apple portable computer batteries are pre-calibrated and do not require the calibration procedure outlined in this article”.