Apple has high markup on their hardware because they spend oodles on R&D. Contrast this with technology cherry picking Dell.
Which brings up an interesting question: are the margins the same or similar for hardware and software after factoring out the cost of R&D for each? If so, maybe the Intel move really is a way to boost software sales while trying to limit decrease in hardware sales and spread risk out a little.
It seems that if Apple "certifies" the quality/stability of OS X on its hardware but allows it to run on other hardware, they have (potentially) the best of both worlds. Those that require stability and/or cool hardware design will continue to go with Apple hardware, whereas the more adventurous / tech savvy will make it work with "unverified" hardware.