Apple today released MacBook Air EFI Firmware Update 2.1 which 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.
For more information about Lion Recovery, please visit http://www.apple.com/macosx/recovery/.
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.
Boot ROM or SMC Version Information: After this update has successfully completed, your Boot ROM Version will be: MBA41.88Z.0077.B08.1109011050
More info and download link (3.99 MB) here.