updated 08:30 pm EDT, Fri May 27, 2011
Even if true, could be just an experiment
Even as Apple is preparing to update the MacBook Air models sometime later this year (possible as early as next month), a Japanese blog has claimed that the company is testing a version of the ultraportable that uses an Apple-designed A5 chip rather than the Intel Core 2 Duo found on current models, PC World reports. The claim could be false -- the report itself says that even if true, it likely to be simply an experiment rather than a planned product.
Apple has never demonstrated a product using their own chips -- the A4 or A5 -- that could run a normal installation of Mac OS X, but the operating system is fairly portable, having made an easy jump from PowerPC based architecture to Intel-based architecture while maintaining a high degree of compatibility. It may indeed be possible to run OS X on an ARM-based chip like the A5, though other factors (such as developers having to re-compile applications to support the chip, and the A5's current lack of support for technologies like Thunderbolt) limit the usefulness of such an idea, even in notebooks aimed at light-duty tasks.
The ARM processors, while powerful enough for the needs of an iPad, are just not yet ready to take on the workload required of a full notebook. The rumor of Apple switching to other processors for its low-end portables has surfaced before, and been debunked.
Even if true, Apple is much more likely to be testing the potential for OS X on future Apple-designed processors generally rather than specifically thinking of releasing an A5-powered MacBook Air, which would at least in the near-term have to be running iOS rather than Mac OS X in order to function.
Much more likely, at least in the short term, say observers, is that the MacBook Air will graduate up to Intel's Core iX series, as well as gain new technologies like Thunderbolt and faster RAM.