On Wednesday afternoon, Apple released a firmware update for the new 11-inch and 13-inch MacBook Air models to address problems with booting and responsiveness.
MacBook Air EFI Firmware Update 2.0 targets two specific issues that Apple says are rare in its latest notebooks: booting to a black screen or simply becoming unresponsive. The update applies to the two newest Air models that Apple announced at its Back to the Mac event in October 2010.
The EFI firmware update is available now via Software Update, even though it has yet to appear on Apple's Support Downloads page. Your MacBook Air will need to be connected to its power adapter in order to install the update, and Software Update will automatically restart your Mac to apply the update once it finishes the small 2.3MB download.