I think there's lots of evidence for that theory. For example, giving away iLife, a package that contained replacements for many of the most common app types, with every Mac. Also, if you look at their Pro apps, like Logic & Final Cut, Apple has consistently undercut the competition agressively, likely as some kind of loss-leader to sell Macs. For example, I remember when Apple bought eMagic (the developers of Logic) they slashed the price from something like $600 to $200, a shockingly low price at the time. All the other software makers had to respond with "lite" versions to compete in this price bracket.