Apple is a bit different. They tend to have a laser focus on a few categories of products and when they introduce a new product, it rarely falters. Other companies try and probe new market segments and consumer interest whereas apple just makes the market segment. On top of that, they make acquisitions to get technologies they wished they had developed, absorbing their R&D and depriving their competitors in one fell swoop.
I agree 100% with Apple being focused and good at what they do. At least lately. In regards to creating segmets: I see a mixed balance sheet.
Apple often leads the way, typically with iOS based devices (iPhone &iPad as well as iTunes)
Sometimes it is falling behind: desktops, notebooks, OS X. I am not comparing to some PC crap at Office Depot, but to windows based mid (beats mac's in price) - or high end stuff (beats mac's in spec's, functionality, design). Slow hardware refresh cycles I guess. EDIT: before fanboy's start screaming, I know mac sales are up. Doesn't change the fact that they are not up to speed.
Sometimes, Apples fails: Apple TV, Gaming consoles (remember Pippin?)
Overall, I think a new market segment is the climax of a long process that had many contibutors. Take iTunes: there was music; there was the internet; there was digital audio and online stores. Apple took all existing elements and combined them. It was more the evolution of already exciting concepts than a revolution.
Cheers