If you take a look at Apple’s Executive Profiles* you’ll note that there is no “executive” responsible for Macintosh hardware or Mac OS X. No doubt the Macintosh and it’s OS fall under Bob Mansfield’s control but his title is “Hardware Engineering” which no doubt is all Apple hardware: Macintosh, iPhone, iPad, iPod, etc.
Apple has a senior executive responsible for iOS software: Scott Forstall, and Eddie Cue is in charge of all of Apple’s online software and services. But no one at this level is responsible for Mac OS X.
This is an indication of just how far Apple has moved from “Apple Computer, Inc.” to Apple, Inc. Apple probably moves more iPhones and iPads in a year than they have Macintosh computers in the entire history of the company (I’m making this up but you get the idea).
This is no doubt a piece of the reason Mac OS X Lion and the upcoming Mountain Lion are inheriting pieces of iOS. There are (many) more iOS users than Mac users.
*Note, the link is working now, apologies to anyone who tried it and got an error.