AppleInsider | Intel also hearing rumors Apple testing MacBooks based on own A-series chip:

An Intel executive said this week it would be foolish to ignore reports that Apple is considering switching some of its Macs away from Intel's mainstream processors and towards its own A-series of mobile chips because it's been hearing the same rumors.

Asked about ARM and Apple's potential use of its A series of ARM processors in future MacBooks, Greg Welch, director of Intel's Ultrabook group, told CNet News.com that the chip maker is taking the threat seriously, and hopes to continue to innovate its way into Apple's product portfolio.