Grab this update if you are an owner of a mid-2011 MacBook Air.
This update includes fixes that enhance the stability of Lion Recovery from an Internet connection, and resolve issues with Apple Thunderbolt Display compatibility and Thunderbolt Target Disk Mode performance on MacBook Air (mid 2011) models.
This is a firmware update, a little different than the normal software update. The update is installed on reboot. So ensure that your Air does not shutdown or lose power halfway through the update.
The MacBook Air EFI Update will update the EFI firmware on your notebook computer. Your computer’s power cord must be connected and plugged into a working power source. When your MacBookAir restarts, a gray screen will appear with a status bar to indicate the progress of the update. It will take several minutes for the update to complete. Do not disturb or shut off the power on your MacBookAir during this update.