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
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.