Apple has issued a firmware update that addresses an issue with Boot Camp and Windows installations for newer MacBook Air models.
MacBook Air EFI Firmware Update 2.7 is recommended for MacBook Air models that came out this year. The update addresses an issue that could cause a black screen to appear when installing Windows 7 or Windows 8 using Boot Camp. This screen would appear when the installation was run while the computer was connected to both an external optical drive and USB thumb drive.
The update also ensures that a system will boot by default into OS X after the installation of Windows 8.
The update is available as a free download at Apple's support page. The 4.8MB download requires a MacBook Air running OS X 10.8.5 or higher.