If rumours and news from SemiAccurate are to be believed, Apple might have chosen the AMD Llano for their new MacBook Air. The current decision of not using them, eventually was done at the last moment. The other option Apple had was Intel’s Sandy Bridge platform, which they finally chose. AMD’s Llano was a low-power option with a better graphics solution than the one used on the Sandy Bridge platform. The Sandy Bridge offers superior CPU performance, as compared to the Llano. The reason for the decision to go with Intel might have to do with supply concerns with AMD. Apple finally went with Core i5 and Core i7 processors with the MacBook Air. Future MacBooks might be different, though. There’s a chance that they might be powered by an ARM-based processor.
Things could've been different?
How well the AMD’s Llanos would have performed on the Apple OS X operating system is not known. Most likely, it would’ve had a slight battery life and better graphics performance than the Sandy Bridge. The decision to choose ARM processors might have to do with when the 64-bit variants start coming out. If it’s anytime soon, the next MacBook Airs are very likely to be powered by them.