None of the products you mention involve leveraging dominant market share in one market to compete in another. You clearly don't understand what I've been saying.
And you clearly don't understand what you just posted. The only significant market that Apple has a large enough market share to be labeled dominant is the digital music player market. And as that market is opening up to competition from smartphone growth (not many people carry an iPod and iPhone), Apple's "dominance" of the market is receding.
Your implication seems to be that their 70% market share in the legal, online digital music download market is another such market. But they compete in digital music sales not only with CD retailers but also with illegal file sharing.
Regardless, they are not leveraging either of these markets in the Palm Pre syncing situation. Palm has unhindered access to iTunes+ music purchased from the iTunes Store. The only "market" that Apple is "leveraging" is the highly contested and valuable "free media sync software" market.
Not much effort involved, Fairplay won't decrypt devices not armed with the decryption keys. Palm doesn't have that and can't get it without Apple giving them.
Except through hacking. But no one would seriously consider that Palm would hack Apple software without permission.