Apple has released a pretty important EFI firmware update for mid 2012 Macbook Airs. It fixes a color issue with external HDMI displays, and also solves problems relating to Windows (surprise, suprise) and Thunderbolt.
It only weighs in at 4.76MB and requires 10.8.2
You can download it via Apple’s website here or via Software Update on your Macbook Air.
From the download page:
This update fixes a color issue with HDMI displays connected to MacBook Air, resolves an issue with Windows which can prevent MacBook Air from booting properly, and also resolves an issue where unplugging a Thunderbolt device may cause the system to freeze when waking from standby.