Today, Apple updated the EFI Firmware for the entire notebook line. MacBook, MacBook Pro, and MacBook Air all received the EFI update. Here's what Apple says about the updates:
This update fixes several issues to improve the stability of [MacBook, MacBook Pro, and MacBook Air] computers.
You can download this update by opening Software Update on your notebook (Apple menu > Software Update) or by downloading the installer package from Apple's support website.
Apple also notes: To complete the firmware update process, please follow the instructions in the updater application (/Applications/Utilities/MacBook EFI Firmware Update.app). The updater will launch automatically when the Installer closes.