An Inability to turn AirPort on or off in some cases after upgrading from Mac OS X Leopard.
An occasional loss of network connection when using Wake on Demand.
An Inability to create a computer-to-computer network, or share the Internet connection on some MacBook, MacBook Pro, and Mac mini computers.
Next, the MacBook and MacBook Pro EFI updates allow the installation of SuperDrive Firmware Update 3.0, reducing the noise of the optical disc drive when waking from sleep and startup. The SuperDrive firmware installation is a 2nd step; you need to do the EFI update, then check again for software updates. This update is available for the Late 2008 aluminum MacBook model and the Early 2009 and Mid 2009 white MacBook models, and for Late 2008 15 inch MacBook Pro models and Early 2009 17 inch MacBook Pro models. (The KB article for the MacBook EFI update may need a little editing, as it refers to a suggestion from a mysterious 'Glenno.')
These updates are available through Software Update, or they're available from Apple's support page.