Owners of the latest MacBook Air models, take note: Apple has just released an EFI firmware update that fixes those pesky problems when trying to use Windows 8 via Boot Camp. Here's what Apple says about the MacBook Air EFI Firmware Update 2.7:
This update is recommended for MacBook Air (mid 2013) models.
This update addresses an issue which may cause a black screen to appear when installing Windows 7 or Windows 8 using Boot Camp Assistant if both an external optical drive and USB thumb drive are connected to the system. This update also ensures that the system will boot by default into OS X after installation of Windows 8.
Owners of the latest MacBook Air can get the firmware update by running Software Update on their Mac or by downloading it directly here.