The Internet is abuzz today in response to Jason Snell's Macworld article arguing that Apple probably will not convert the Mac to an ARM processor. ARM processors are currently being designed by Apple for use in the iPhone and iPad and their custom chips are one of the reasons they are so far ahead of the competition on mobile processors.
Lately, the Mac has been taking heat for the slow upgrade cycle, Part of the blame (but not all of it) falls on Apple's current Mac chip manufacturer, Intel, for missing deadlines. Jason makes the argument that Apple will, in all likelihood, stay with Intel because the Mac doesn't earn enough money for Apple to justify the substantial cost of time and money to make a transition to a new processor.
I can't help but think that Apple's tendency to want to control everything would probably be enough for them to commit resources to switching to ARM. If Apple designs their own silicon, they'll never rely on Intel again. Also, with the ever increasing race for better battery life, I'd expect Apple could make a MacBook that runs a very long time on an ARM-based chip. Jason Snell's a pretty smart guy and been around this racket much longer than I but I wouldn't be surprised if Apple does bring ARM to the Mac at some point, even if it is just the lower-powered, super-long battery MacBooks.