Apple tonight released MacBook Air EFI Firmware Update 1.0 (2.1MB) via software update. According to Apple, the update "fixes several issues to improve the stability of MacBook Air computers." Whatever that means.
After the firmware is successfully applied to your Mac, your Boot ROM Version will be: MBA11.00BB.B03.
You can confirm the version of the BootROM installed on your computer using System Profiler.
Once you download the update, you must run the Firmware Updater (located in /Applications/Utilities/MacBook Air EFI Firmware Update.app) and follow the enclosed instructions for the update to take effect.
Your computer's power cord must be connected and plugged into a working power source.
To update the firmware on your Intel-based MacBook Air:
Quit all other open applications.
Click Shut Down in the MacBook Air EFI Firmware Update window and wait for your computer to shut down.
Press and release the power button on your MacBook Air.
A status bar indicates the progress of the update.
Important: Do not interrupt the update. It will take a couple of minutes for the update to complete.
Your computer restarts automatically when the update is completed and the MacBook Air EFI Firmware Update will confirm your firmware is now up-to-date.
Previous EFI Firmware updates have addressed issues with Boot Camp and fixed fan behavior on the MacBook Pro and Mac Pro. On 10 March 2008 Apple released the MacBook Air SMC Firmware Update which "fine tunes the speed and operation of the internal fan."