Apple has released a new update for the MacBook Air which contained clues on changes for the notbook's battery.
Apple has confirmed that the changes included in the firmware for the MacBook Air point towards a new series or replacement batteries. Before everyone gets excited, Apple still plans on them not being user replaceable so that you will still have to take your MacBook Air to an authorized service repair center to have the battery replaced.
Apple says that they are increasingly using advanced chemistry combined with adaptive charging to improve battery life and in their defense they have someof the longest lasting batteries on the market. The new batteries don't seem to be the silver-zinc batteries that Apple has been working on but still just the lithium batteries that they have been using.