Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
No, AppleCare will not cover a battery, unless it is defective.

b. Limitations. The Plan does not cover:
(ix) Consumable parts, such as batteries, except in respect of battery coverage under APP for iPod or unless failure has occurred due to a defect in materials and workmanship;
 
That is what happened to my battery. Just after two years my battery started to slightly bulge and dropped from holding a charge 2+ hours to being able to run for about 5-10 minutes. So the genius bar replaced it under my applecare at that point.
 
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.