Apple officials have confirmed with MacFixIt that the MacBook Air can startup from remote optical media via the Remote Disc function. We asked Janette Barrios, Apple spokesperson for Desktops and Notebooks: "Does the Remote Disc function allows booting the system. In other words, could you put a Mac OS X Install disc in a remote computer then boot the MacBook Air from that disc?" She answered "Answer is yes, you can."
We assume that a startup key can be used to invoke Remote Disc booting (invoking a NetBoot under Mac OS X requires holding the N key at startup, while starting from an optical disc requires holding the C key), but are awaiting further details.
This news assuages some of our previously posted troubleshooting-related concerns regarding the MacBook Air, though emergency boots will still necessitate the presence of a nearby Mac/PC or an external USB drive (hard drive or optical).