Airport Update

Apple has released an Airport Update for certain MacBooks and MacBook Pros:

This update is recommended for some Intel-based Macintosh computers running Mac OS X v10.5.8 and addresses an issue with AirPort performance while running on battery power. It may only be installed on:

MacBook (13-inch, Late 2007)
MacBook (13-inch, Early 2008)
MacBook (13-inch, Late 2008)
MacBook Pro (15-inch, Early 2008)
MacBook Pro (17-inch, Early 2008)
MacBook Pro (17-inch, Late 2008)

It can be downloaded via Software Update or from the following address:
http://support.apple.com/downloads/AirPort_Client_Update_for_MacBook_and_MacBook_Pro