MacRumors.com

Apple has posted Battery Update 1.2, which updates battery firmware and improves battery functionality according to Apple.

The update affects most Intel-based notebooks, including:
* MacBook
* MacBook (Late 2006)
* MacBook Pro (15-inch)
* MacBook Pro (15-inch Glossy)
* MacBook Pro (15-inch Core 2 Duo)
* MacBook Pro (17-inch)
* MacBook Pro (17-inch Core 2 Duo)

More information about the update can be found in this knowledge-base article.

Update: Macworld has posted a statement from Apple regarding the update. Apple has apparently recently identified an issue that was causing poor performance.

"We have issued a software update that is designed to improve battery performance, and consumers can receive a new battery free of charge if their battery continues to have performance issues after installing the software update, even if their computer is out of warranty," said Apple in a statement provided to Macworld.

According to Macworld, no safety issue has been identified; the update is limited purely to performance concerns.

Update 2: Apple has added another support page for the battery update. Highlights are:

* If, after installing the update, your computer continues to exhibit below symptoms, you may be eligible to receive free out-of-warranty replacement of your battery.
* The warranty on the batteries of MacBook and MacBook Pro systems with Core 2 Duo processors has been extended to 2 years from the date of purchase.

Symptoms of an affected battery:
* Battery is not recognized causing an “X” to appear in the battery icon in the Finder menu bar.
* Battery will not charge when computer is plugged into AC power.
* Battery exhibits low charge capacity/runtime when using a fully charged battery with a battery cycle count (as shown in System Profiler) of less than 300.
* Battery pack is visibly deformed.